GHSA-hrxh-6v49-42gf
gRPC-Go: xDS RBAC and HTTP/2 Vulnerabilities
Blast Radius
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Description
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
MetadataorRequestedServerNamefields. - 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
NOTrules 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
permissionandprincipalrules (specificallyMetadataandRequestedServerName) 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
NOTrules (Permission_NotRule/Principal_NotId) or multi-conditionOR/ANDrules, 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
SETTINGSACKs or server-initiatedRST_STREAMs.
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
NOTrule wrapped an unsupported or unhandled field (such asSourcedMetadata), 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, orNOTrules wrapping unsupported fields (such asSourcedMetadata) 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_streamslimits and active rate limiting onRST_STREAMfrequency 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 |
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | google.golang.org/grpc | all versions | 1.82.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for google.golang.org/grpc. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update google.golang.org/grpc to 1.82.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hrxh-6v49-42gf is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-hrxh-6v49-42gf is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-hrxh-6v49-42gf. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-hrxh-6v49-42gf in your dependencies?
O3 detects GHSA-hrxh-6v49-42gf across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.