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ringhash: enable behaviors of A76 by default - #8922

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Feb 23, 2026
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ringhash: enable behaviors of A76 by default#8922
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atollena:enable-a76-by-default

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@atollena

@atollena atollena commented Feb 20, 2026

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Those features have been gated by environment variables since 1.73.0, and used in production at Datadog. They can be considered stable.

Change the defaults to enable using EDS hash_key lb metadata and requestHashHeader LB config field.

RELEASE NOTES:

  • ringhash: Enable A76 ring hash improvements by default: EDS endpoint hash key parsing from LbEndpoint metadata and request hash header support via the "requestHashHeader" field. The previous behavior can be restored by setting GRPC_XDS_ENDPOINT_HASH_KEY_BACKWARD_COMPAT=true or GRPC_EXPERIMENTAL_RING_HASH_SET_REQUEST_HASH_KEY=false.

Those features have been gated by environment variables since 1.73.0, and used
in production at Datadog. They can be considered stable.

Change the defaults to enable using eds hash_key lb metadata and
set_request_hash key.

RELEASE NOTES:
- ringhash: Enable A76 ring hash improvements by default: EDS endpoint hash
  key parsing from LbEndpoint metadata and request hash header support via
  the "requestHashHeader" field. The previous behavior can be restored by
  setting GRPC_XDS_ENDPOINT_HASH_KEY_BACKWARD_COMPAT=true or
  GRPC_EXPERIMENTAL_RING_HASH_SET_REQUEST_HASH_KEY=false.
@atollena atollena added Type: Feature New features or improvements in behavior Area: Resolvers/Balancers Includes LB policy & NR APIs, resolver/balancer/picker wrappers, LB policy impls and utilities. labels Feb 20, 2026
@atollena atollena added this to the 1.80 Release milestone Feb 20, 2026
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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.20%. Comparing base (19e4128) to head (f47dce7).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files
@@            Coverage Diff             @@
##           master    #8922      +/-   ##
==========================================
- Coverage   83.30%   83.20%   -0.11%     
==========================================
  Files         417      417              
  Lines       32940    32940              
==========================================
- Hits        27442    27407      -35     
- Misses       4082     4111      +29     
- Partials     1416     1422       +6     
Files with missing lines Coverage Δ
internal/envconfig/envconfig.go 100.00% <ø> (ø)

... and 29 files with indirect coverage changes

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@easwars

easwars commented Feb 20, 2026

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@arjan-bal : For second set of eyes

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LGTM

@arjan-bal
arjan-bal merged commit 4a83bf9 into grpc:master Feb 23, 2026
14 of 18 checks passed
This was referenced Apr 23, 2026
nschloe pushed a commit to live-clones/forgejo that referenced this pull request Jul 23, 2026
…/forgejo) (#13580)

This PR contains the following updates:

| Package | Change | [Age](https://docs.renovatebot.com/merge-confidence/) | [Confidence](https://docs.renovatebot.com/merge-confidence/) |
|---|---|---|---|
| [google.golang.org/grpc](https://github.com/grpc/grpc-go) | `v1.79.3` → `v1.82.1` | ![age](https://developer.mend.io/api/mc/badges/age/go/google.golang.org%2fgrpc/v1.82.1?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/go/google.golang.org%2fgrpc/v1.79.3/v1.82.1?slim=true) |

---

### gRPC-Go: xDS RBAC and HTTP/2 Vulnerabilities
[GHSA-hrxh-6v49-42gf](GHSA-hrxh-6v49-42gf)

<details>
<summary>More information</summary>

#### Details
Multiple security vulnerabilities have been identified and addressed in grpc-go affecting the xDS RBAC authorization engine (internal/xds/rbac) and the HTTP/2 transport server implementation (internal/transport). These vulnerabilities could result in:

- Authorization Bypass (Fail-Open) when translating xDS RBAC policies containing `Metadata` or `RequestedServerName` fields.
- Denial of Service (High CPU Consumption) due to an HTTP/2 Rapid Reset mitigation bypass during client-initiated stream resets.
- Denial of Service (Server Panic) when parsing crafted xDS RBAC policies containing `NOT` rules around unsupported fields.

##### Impact
_What kind of vulnerability is it? Who is impacted?_

##### xDS RBAC Authorization Bypass via `Metadata` & `RequestedServerName` matchers

- Affected Component: xDS RBAC
- Impact: When building policy matchers for gRPC RBAC from xDS configurations, unsupported `permission` and `principal` rules (specifically `Metadata` and `RequestedServerName`) were silently ignored and treated as no-ops.
  - If an authorization policy relied purely on these matchers for access control, treating those rules as no-ops effectively removed the restrictions.
- If these unsupported rules were nested inside logical `NOT` rules (`Permission_NotRule` / `Principal_NotId`) or multi-condition `OR/AND` rules, silently dropping them changed the boolean logic flow of the authorization engine.

As a result, policy evaluation decisions could fail open, allowing unauthorized clients to access protected gRPC services or resources.

##### HTTP/2 Rapid Reset Mitigation Bypass / Denial of Service via Stream Aborts

- Affected Component: HTTP/2 transport
- Impact: Earlier mitigations in grpc-go for HTTP/2 Rapid Reset only applied threshold checks to items that directly resulted in control frames being written back to the wire, such as `SETTINGS` ACKs or server-initiated `RST_STREAM`s.

When a client initiated a rapid flood of stream creation (`HEADERS`) immediately followed by stream termination `RST_STREAM`, items queued up in the control buffer without counting against the transport response frame threshold. An attacker can repeatedly trigger this flood sequence to bypass reader blocking, resulting in high CPU usage, and Denial of Service (DoS).

##### Denial of Service (Panic) in xDS RBAC Engine via Unsupported Fields inside NOT Rules

- Affected Component: xDS RBAC
- Impact: The xDS RBAC policy translators recursively generate matchers for nested rules. When a `NOT` rule wrapped an unsupported or unhandled field (such as `SourcedMetadata`), the recursive step returned an empty matcher. This could result in a runtime panic when the RBAC engine attempts to authorize an incoming request.

An attacker or misconfigured/malicious xDS management server delivering an LDS/RDS update containing a `NOT` rule around an unhandled field causes the gRPC server process to crash immediately (CWE-248 / Denial of Service).

##### Patches
_Has the problem been patched? What versions should users upgrade to?_

All three issues have been fixed in `master` and will be released in 1.82.1 shortly.

##### Workarounds
_Is there a way for users to fix or remediate the vulnerability without upgrading?_

If upgrading grpc-go immediately is not possible, apply the following workarounds based on your deployment architecture:

* For xDS RBAC Vulnerabilities & Panics: Ensure that upstream xDS management servers do not push RBAC policies containing `Metadata`, `RequestedServerName`, or `NOT` rules wrapping unsupported fields (such as `SourcedMetadata`) to grpc-go servers.
* For HTTP/2 Rapid Reset DOS: Configure upstream reverse proxies or load balancers (such as Envoy) with strict HTTP/2 `max_concurrent_streams` limits and active rate limiting on `RST_STREAM` frequency per connection.

##### Severity

  | Vulnerability | Qualitative Severity | Approximate CVSS v3.1 Score | Primary Impact |
  | :--- | :--- | :--- | :--- |
  | **xDS RBAC Authorization Bypass** | **High** | `8.2` | Unauthorized Access / Fail-Open |
  | **HTTP/2 Rapid Reset DOS Bypass** | **High** | `7.5` | High CPU Consumption / Denial of Service |
  | **xDS RBAC Engine Server Panic** | **Medium** | `5.9` | Process Crash / Denial of Service |

#### Severity
- CVSS Score: 8.8 / 10 (High)
- Vector String: `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N`

#### References
- [https://github.com/grpc/grpc-go/security/advisories/GHSA-hrxh-6v49-42gf](https://github.com/grpc/grpc-go/security/advisories/GHSA-hrxh-6v49-42gf)
- [https://github.com/grpc/grpc-go/pull/9236](https://github.com/grpc/grpc-go/pull/9236)
- [https://github.com/grpc/grpc-go/commit/4ea465d4ab98013f72a142fe0fc89c19770b2935](https://github.com/grpc/grpc-go/commit/4ea465d4ab98013f72a142fe0fc89c19770b2935)
- [https://github.com/grpc/grpc-go](https://github.com/grpc/grpc-go)
- [https://github.com/grpc/grpc-go/releases/tag/v1.82.1](https://github.com/grpc/grpc-go/releases/tag/v1.82.1)

This data is provided by [OSV](https://osv.dev/vulnerability/GHSA-hrxh-6v49-42gf) and the [GitHub Advisory Database](https://github.com/github/advisory-database) ([CC-BY 4.0](https://github.com/github/advisory-database/blob/main/LICENSE.md)).
</details>

---

### Release Notes

<details>
<summary>grpc/grpc-go (google.golang.org/grpc)</summary>

### [`v1.82.1`](https://github.com/grpc/grpc-go/releases/tag/v1.82.1): Release 1.82.1

[Compare Source](grpc/grpc-go@v1.82.0...v1.82.1)

### Security

- server: Stop reading from the connection when flooded by HTTP/2 frames.  The default value for this limit is 100 frames, excluding DATA and HEADERS, and may be changed by setting environment variable `GRPC_GO_EXPERIMENTAL_CONTROL_BUFFER_THROTTLE_LIMIT`.
- xds/rbac: Support `Metadata` and `RequestedServerName` permissions matcher fields.  If present in a DENY rule, previously these would be ignored and fail-open.
- xds/rbac: Fix panic when parsing unsupported fields in `NotRule`/`NotId` permissions.
- xds/rbac: Support the deprecated `source_ip` principal identifier by treating it as equivalent to `direct_remote_ip`.

### [`v1.82.0`](https://github.com/grpc/grpc-go/releases/tag/v1.82.0): Release 1.82.0

[Compare Source](grpc/grpc-go@v1.81.1...v1.82.0)

### Behavior Changes

- server: Remove support for `GRPC_GO_EXPERIMENTAL_DISABLE_STRICT_PATH_CHECKING` environment varibale. Strict incoming RPC path validation (which has been the default since `v1.79.3`) can no longer be disabled. ([#&#8203;9112](grpc/grpc-go#9112))
- transport: Add environment variable to change the default max header list size from `16MB` to `8KB`. This may be enabled by setting `GRPC_GO_EXPERIMENTAL_ENABLE_8KB_DEFAULT_HEADER_LIST_SIZE=true`. This will be enabled by default in a subsequent release. ([#&#8203;9019](grpc/grpc-go#9019))
- balancer: Load Balancing policy registry is now case-sensitive.  Set `GRPC_GO_EXPERIMENTAL_CASE_SENSITIVE_BALANCER_REGISTRIES=false` (and file an issue) to revert to case-insensitive behavior. ([#&#8203;9017](grpc/grpc-go#9017))

### New Features

- experimental/stats: Expose a new API, `NewContextWithLabelCallback`, to register a callback that is invoked when telemetry labels are added. ([#&#8203;8877](grpc/grpc-go#8877))
  - Special Thanks: [@&#8203;seth-epps](https://github.com/seth-epps)
- client: Return a portion of the response body in the error message, when the client receives an unexpected non-gRPC HTTP response, to make debugging easier. ([#&#8203;8929](grpc/grpc-go#8929))
  - Special Thanks: [@&#8203;chengxilo](https://github.com/chengxilo)
- server: Add environment variable `GRPC_GO_SERVER_GOROUTINE_LABELS` that controls setting `runtime/pprof.Labels` on goroutines spawned by the server. Set `GRPC_GO_SERVER_GOROUTINE_LABELS=grpc.method=true` to add the `grpc.method` label on goroutines spawned to handle incoming requests. ([#&#8203;9082](grpc/grpc-go#9082))
  - Special Thanks: [@&#8203;dfinkel](https://github.com/dfinkel)

### Bug Fixes

- xds/server: Fix a memory leak of HTTP filter instances occurring when route configurations are updated in-place during a Route Discovery Service (RDS) update. ([#&#8203;9138](grpc/grpc-go#9138))
- grpc: In the deprecated `gzip` Compressor (used via the deprecated `WithCompressor` dial option), enforce the `MaxRecvMsgSize` limit on the decompressed message buffer, preventing excessive memory allocation from highly compressed payloads. ([#&#8203;9114](grpc/grpc-go#9114))
  - Special Thanks: [@&#8203;evilgensec](https://github.com/evilgensec)
- stats/opentelemetry: Record retry attempts, `grpc.previous-rpc-attempts`, at the call level and not the attempt level. ([#&#8203;8923](grpc/grpc-go#8923))
- encoding: Ensure `Close()` is always called on readers returned from `Compressor.Decompress` if possible. ([#&#8203;9135](grpc/grpc-go#9135))
- channelz: Fix the `LastMessageSentTimestamp` and `LastMessageReceivedTimestamp` fields in `SocketMetrics` to ensure they contain correct timestamp values. ([#&#8203;9109](grpc/grpc-go#9109))

### [`v1.81.1`](https://github.com/grpc/grpc-go/releases/tag/v1.81.1): Release 1.81.1

[Compare Source](grpc/grpc-go@v1.81.0...v1.81.1)

### Security

- xds/rbac: Fix a potential authorization bypass caused by incorrectly falling through URI/DNS SANs to Subject Distinguished Name (DN) when matching the authenticated principal name. With this fix, only the first non-empty identity source will be used, as per [gRFC A41](https://github.com/grpc/proposal/blob/master/A41-xds-rbac.md). ([#&#8203;9111](grpc/grpc-go#9111))
  - Special Thanks: [@&#8203;al4an444](https://github.com/al4an444)

### Bug Fixes

- otel: Segregate client and server RPC information used for metrics and traces, to avoid one overwriting the other. ([#&#8203;9081](grpc/grpc-go#9081))

### [`v1.81.0`](https://github.com/grpc/grpc-go/releases/tag/v1.81.0): Release 1.81.0

[Compare Source](grpc/grpc-go@v1.80.0...v1.81.0)

### Behavior Changes

- balancer/rls: Switch gauge metrics to asynchronous emission (once per collection cycle) to reduce telemetry noise and align with other gRPC language implementations. ([#&#8203;8808](grpc/grpc-go#8808))

### Dependencies

- Minimum supported Go version is now 1.25. ([#&#8203;8969](grpc/grpc-go#8969))

### Bug Fixes

- xds: Use the leaf cluster's security config for the TLS handshake instead of the aggregate cluster's config. ([#&#8203;8956](grpc/grpc-go#8956))
- transport: Send a `RST_STREAM` when receiving an `END_STREAM` when the stream is not already half-closed. ([#&#8203;8832](grpc/grpc-go#8832))
- xds: Fix ADS resource name validation to prevent a panic. ([#&#8203;8970](grpc/grpc-go#8970))

### New Features

- grpc/stats: Add support for custom labels in per-call metrics ([gRFC A108](https://github.com/grpc/proposal/blob/master/A108-otel-custom-per-call-label.md)). ([#&#8203;9008](grpc/grpc-go#9008))
- xds: Add support for Server Name Indication (SNI) and SAN validation ([gRFC A101](https://github.com/grpc/proposal/blob/master/A101-SNI-setting-and-SNI-SAN-validation.md)). Disabled by default. To enable, set `GRPC_EXPERIMENTAL_XDS_SNI=true` environment variable. ([#&#8203;9016](grpc/grpc-go#9016))
- xds: Add support to control which fields get propagated from ORCA backend metric reports to LRS load reports ([gRFC A85](https://github.com/grpc/proposal/blob/master/A85-lrs-custom-metrics-changes.md)). Disabled by default. To enable, set `GRPC_EXPERIMENTAL_XDS_ORCA_LRS_PROPAGATION=true`. ([#&#8203;9005](grpc/grpc-go#9005))
- xds: Add metrics to track xDS client connectivity and cached resource state ([gRFC A78](https://github.com/grpc/proposal/blob/master/A78-grpc-metrics-wrr-pf-xds.md)). ([#&#8203;8807](grpc/grpc-go#8807))
- stats/otel: Enhance `grpc.subchannel.disconnections` metric by adding disconnection reason to the `grpc.disconnect_error` label ([gRFC A94](https://github.com/grpc/proposal/blob/master/A94-subchannel-otel-metrics.md)). This provides granular insights into why subchannels are closing. ([#&#8203;8973](grpc/grpc-go#8973))
- mem: Add `mem.Buffer.Slice()` API to slice the buffer like a slice. ([#&#8203;8977](grpc/grpc-go#8977))
  - Special Thanks: [@&#8203;ash2k](https://github.com/ash2k)

### Performance Improvements

- alts: Pool read buffers to lower memory utilization when sockets are unreadable. ([#&#8203;8964](grpc/grpc-go#8964))
- transport: Pool HTTP/2 framer read buffers to reduce idle memory consumption. Currently limited to Linux for ALTS and non-encrypted transports (TCP, Unix). To disable, set `GRPC_GO_EXPERIMENTAL_HTTP_FRAMER_READ_BUFFER_POOLING=false` and report any issues. ([#&#8203;9032](grpc/grpc-go#9032))

### [`v1.80.0`](https://github.com/grpc/grpc-go/releases/tag/v1.80.0): Release 1.80.0

[Compare Source](grpc/grpc-go@v1.79.3...v1.80.0)

### Behavior Changes

- balancer: log a warning if a balancer is registered with uppercase letters, as balancer names should be lowercase. In a future release, balancer names will be treated as case-insensitive; see [#&#8203;5288](grpc/grpc-go#5288) for details. ([#&#8203;8837](grpc/grpc-go#8837))
- xds: update resource error handling and re-resolution logic ([#&#8203;8907](grpc/grpc-go#8907))
  - Re-resolve all `LOGICAL_DNS` clusters simultaneously when re-resolution is requested.
  - Fail all in-flight RPCs immediately upon receipt of listener or route resource errors, instead of allowing them to complete.

### Bug Fixes

- xds: support the LB policy configured in `LOGICAL_DNS` cluster resources instead of defaulting to `pick_first`. ([#&#8203;8733](grpc/grpc-go#8733))
- credentials/tls: perform per-RPC authority validation against the leaf certificate instead of the entire peer certificate chain. ([#&#8203;8831](grpc/grpc-go#8831))
- xds: enabling A76 ring hash endpoint keys no longer causes EDS resources with invalid proxy metadata to be NACKed when HTTP CONNECT (gRFC A86) is disabled. ([#&#8203;8875](grpc/grpc-go#8875))
- xds: validate that the sum of endpoint weights in a locality does not exceed the maximum `uint32` value. ([#&#8203;8899](grpc/grpc-go#8899))
  - Special Thanks: [@&#8203;RAVEYUS](https://github.com/RAVEYUS)
- xds: fix incorrect proto field access in the weighted round robin (WRR) configuration where `blackout_period` was used instead of `weight_expiration_period`. ([#&#8203;8915](grpc/grpc-go#8915))
  - Special Thanks: [@&#8203;gregbarasch](https://github.com/gregbarasch)
- xds/rbac: handle addresses with ports in IP matchers. ([#&#8203;8990](grpc/grpc-go#8990))

### New Features

- ringhash: enable gRFC A76 (endpoint hash keys and request hash headers) by default. ([#&#8203;8922](grpc/grpc-go#8922))

### Performance Improvements

- credentials/alts: pool write buffers to reduce memory allocations and usage. ([#&#8203;8919](grpc/grpc-go#8919))
- grpc: enable the use of pooled write buffers for buffering HTTP/2 frame writes by default. This reduces memory usage when connections are idle. Use the [WithSharedWriteBuffer](https://pkg.go.dev/google.golang.org/grpc#WithSharedWriteBuffer) dial option or the [SharedWriteBuffer](https://pkg.go.dev/google.golang.org/grpc#SharedWriteBuffer) server option to disable this feature. ([#&#8203;8957](grpc/grpc-go#8957))
- xds/priority: stop caching child LB policies removed from the configuration. This will help reduce memory and cpu usage when localities are constantly switching between priorities. ([#&#8203;8997](grpc/grpc-go#8997))
- mem: add a faster tiered buffer pool; use the experimental [mem.NewBinaryTieredBufferPool](https://pkg.go.dev/google.golang.org/grpc/mem@master#NewBinaryTieredBufferPool) function to create such pools. ([#&#8203;8775](grpc/grpc-go#8775))

</details>

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Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/13580
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