Back to the CVE list
CVE-2026-84303

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

CVSS score

6.3

EPSS probability

%0.3

Risk score

0.0

Published

1 mo ago

OverviewPublic Exploits (0)NewsroomVulnerability Timeline
Official patch verified

Etkilenen ürün ve sürüm için yayımlanan güvenlik güncellemesini uygulayın.

Impact on My Inventory

Only the personal products you have added to your account are assessed; an organisation's inventory does not appear here.

Checking session…

Vulnerability description

DayBreach CVE AI Research

CVE-2026-84303 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.

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.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-84303 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1grpcgrpc-go View
2gogoogle.golang.org/grpc View
3gogoogle.golang.org/grpc View
Total affected vendors: 2|Products: 3

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
6.3CVSS V4_0MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:NCVE CNA
6.3CVSS V40MEDIUMCVSS: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:XNVD
6.3CVSS 4.0—Vector not publishedGitHub Advisory

Patch and Remediation Guide

Solution & Remediation Advisory

Patch verified

1 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

gitlabgo/google.golang.org/grpc1.83.1

GitLab Advisory düzeltilmiş sürüm: 1.83.1

gitlab

Upgrade to version 1.83.1 or above.

canonical

Upgrade to version 1.83.1 or above.

Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Apply the official update named in the evidence only to the matching product and version.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-84303 is associated with the following CWEs:

CWE-178: Common Weakness Enumeration Entry CWE-178CWE-863: Common Weakness Enumeration Entry CWE-863CWE-937: Common Weakness Enumeration Entry CWE-937CWE-1035: Common Weakness Enumeration Entry CWE-1035

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-84303 weaknesses.

CAPEC-66: SQL InjectionCAPEC-126: Path TraversalCAPEC-28: OS Command Injection

Attack Vector and Accessibility

ExposureAğ üzerinden
PermissionsGerekmiyor
UserGerekmiyor

Official Sources and Advisories

https://github.com/grpc/grpc-go/security/advisories/GHSA-qc2q-p7wx-3px3vendor-advisoryhttps://github.com/grpc/grpc-go/pull/9332vendor-advisoryhttps://github.com/grpc/grpc-go/pull/9335vendor-advisoryhttps://github.com/grpc/grpc-go/commit/db9482836c298f234c896cf82ab68cafc78237f8vendor-advisoryhttps://github.com/grpc/grpc-go/commit/ebba6f3f1b206e2b4dc4d1d5a96d18430302c2fevendor-advisoryhttps://github.com/grpc/grpc-go/releases/tag/v1.83.1vendor-advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2026-84303vendor-advisoryhttps://github.com/advisories/GHSA-qc2q-p7wx-3px3vendor-advisory

CVSS Vector Radar Chart

6.3 / 10
Attack VectorNetworkComplexityLowPrivilegesNoneUser Interact.NoneConfidentialityLowIntegrityNoneAvailabilityNone

Vulnerability Scoring Details

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
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone required
User InteractionNone required
Confidentiality (Gizlilik)Low
Integrity (Bütünlük)None
Availability (Erişilebilirlik)None

Yama doğrulandı

1 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

Follow the vendor

G
grpc logo
grpc
G
go logo
go

Weakness Type (CWE & CAPEC)

CWE-178 CWE-863 CWE-937 CWE-1035

Similar Vulnerabilities

Get this vulnerability through the API

Affected products, version ranges, exploitation status and patch information in a single request, with a free key.

Get a free keyDocumentation
curl -H "x-api-key: $DAYBREACH_API_KEY" \
  "https://api.enginteksut.com.tr/api/v1/intel/cves/CVE-2026-84303"