GHSA-qc2q-p7wx-3px3Published

gRPC-Go: xDS RBAC HTTP Filter bypass via mixed-case Header Matching and gRFC A41 validation evasion

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cve-program · CVE-2026-84303

Published

gRPC-Go is the Go language implementation of gRPC. Prior to 1.83.1, the xDS RBAC HTTP filter in internal/xds/httpfilter/rbac/rbac.go does not lowercase header matcher names in normalizeHeaderMatcher even though incoming metadata keys are lowercase. A DENY policy using a mixed-case name such as X-Role or User-Agent therefore does not match and fails open, allowing requests that should be rejected. The same case mismatch permits :Scheme or Grpc-Status to evade gRFC A41 validation and prevents Host from being rewritten to :authority. This issue is fixed in version 1.83.1.

Source published: 1 Sep 2026 18:14:37 UTC
Source modified: 2 Sep 2026 19:14:49 UTC
Saved here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 4.0 · 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

euvd · EUVD-2026-69419

Published

Additional publisher context

EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.

Original publisher date fields

datePublished: Sep 1, 2026, 6:14:37 PM

dateUpdated: Sep 2, 2026, 7:14:49 PM

51 related source bulletins · separate from aliases

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openSUSE-SU-2026:11713-1: trivy-0.74.0-4.1 on GA media

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msrc_CVE-2026-84303: gRPC-Go: xDS RBAC HTTP Filter bypass via mixed-case Header Matching and gRFC A41 validation evasion

CVE-2026-84303

openSUSE-SU-2026:12114-1: alloy-1.20.1-1.1 on GA media

CVE-2026-14362 · CVE-2026-63209 · CVE-2026-81871 · CVE-2026-81872 · CVE-2026-84303 · CVE-2026-84304 · CVE-2026-84445

openSUSE-SU-2026:11743-1: google-osconfig-agent-20260908.00-1.1 on GA media

CVE-2026-84303 · CVE-2026-84445

Source published: Sep 1, 2026, 6:14:37 PM (timezone not stated)
Source modified: Sep 2, 2026, 7:14:49 PM (timezone not stated)
Saved here: 11 Nov 2026 17:00:50 UTC
Source terms: ENISA EUVD · source terms and attribution apply

Original source record · Cite this exact observation · Complete original publisher JSON

Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

EUVD CVSS 4.0 · 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

nvd · CVE-2026-84303

Published

Additional publisher context

NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Deferred

Weakness classifications: CWE-178 · CWE-863

Original publisher date fields

published: 2026-09-01T19:17:30.600

lastModified: 2026-09-09T21:09:13.080

Source published: 1 Sep 2026 19:17:30 UTC
Source modified: 9 Sep 2026 21:09:13 UTC
Saved here: 25 Oct 2026 16:19:16 UTC
Source terms: NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 4.0 · [email protected] · Secondary · 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

osv · GHSA-qc2q-p7wx-3px3

Published

### Summary A vulnerability in the xDS RBAC HTTP filter implementation in grpc-go allows remote attackers to bypass authorization policies (specifically DENY rules) by using mixed-case or canonical-case header matchers (e.g., X-Role instead of x-role). Additionally, the safety guards introduced by gRFC A41 to block grpc- prefixed headers can be evaded via variations in casing (e.g., Grpc-Status). ### Impact When an operator defines an RBAC policy referencing headers containing uppercase letters (e.g. X-Role), grpc-go fails to match incoming metadata keys because they are unconditionally lowercased. Because of this case-sensitivity mismatch, a policy designed to block requests containing specific header values fails open: the rule is evaluated as a non-match, and traffic that should have been rejected is served. Furthermore, gRFC A41 requires rejecting configuration schemas specifying header matchers starting with grpc-. Because this check is executed case-sensitively in grpc-go, attackers can bypass the validation by specifying titles like Grpc-Status. ### Patches The problem is fixed in `master` and in the 1.83.1 release.

Source published: 8 Sep 2026 20:50:21 UTC
Source modified: 15 Sep 2026 19:10:32 UTC
Saved here: 24 Oct 2026 13:19:41 UTC
Source terms: GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Publisher rating · MODERATE

osv · GO-2026-6441

Published

In google.golang.org/grpc, the xDS RBAC HTTP filter does not lowercase header matcher names before evaluating them against incoming request metadata. When an RBAC policy defines rules (such as DENY) referencing headers with uppercase or mixed-case characters, the rule fails to match, causing authorization policies to fail open. Additionally, callers can evade gRFC A41 validation blocking "grpc-" prefixed headers and ":scheme" via variations in casing.

Source published: 15 Sep 2026 18:39:25 UTC
Source modified: 15 Sep 2026 19:00:17 UTC
Saved here: 24 Oct 2026 13:19:41 UTC
Source terms: OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

Source: osv · OSV · upstream source license applies. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.