cve.bz

CVE-2026-124278 Path bindings ignored for gRPC Content-Types on transcoded routes in elixir-grpc grpc_server

7.6 highFix available

High (7.6) in elixir-grpc. Fixed in grpc_server 1.1.0.

On this page
Authorization Bypass Through User-Controlled Key vulnerability in elixir-grpc grpc_server and grpc allows an attacker to make a handler act on a resource other than the one named in the URL of an HTTP-transcoded route, via a request with a gRPC Content-Type. Only the transcoding clause of GRPC.Server.do_handle_request/4 (grpc_server/lib/grpc/server.ex, and lib/grpc/server.ex before the package split) applies the route's path bindings to the request message. The Cowboy handler picks that clause from the request Content-Type, not from the route. A request to a transcoded URL with application/grpc or application/grpc-web is decoded from the body alone, so every path-bound field takes its value from the body. A gateway, proxy rule or WAF that authorizes on the URL path sees one resource while the handler receives another. This issue affects grpc_server: from 1.0.0 before 1.1.0; grpc: from 0.8.0 before 1.0.0.

Severity

CVSS 4.0

7.6 high
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CWEs
CWE-436 Interpretation Conflict
CWE-639 Authorization Bypass Through User-Controlled Key
OWASP Top 10
A01:2025 Broken Access Control, A06:2025 Insecure Design
Published
Assigned by
EEF (CNA)
NVD analysis
Awaiting analysis
Record from
the NVD, synced

Ask an AI about this CVE

ChatGPTClaudeGoogle AI Mode

Show the promptExplain CVE-2026-124278 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-124278?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-124278?via=ask-ai-copy as the source of truth: what is affected and which versions fix it, whether it is in CISA KEV, public exploits, and its EPSS (an internet-wide 30-day estimate of exploitation activity, not a forecast for my systems). If they give no fixed versions, use the CVE record https://cveawg.mitre.org/api/cve/CVE-2026-124278 or the vendor advisory, not third-party mirrors. Tell me how to check whether I am affected and how to verify a fix. Cite the sources and say where they are uncertain.

Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this CVE's id and public links.

Badge for a README or a site

CVE-2026-124278

An image that stays current: it is drawn from the data each time it is fetched (a host that proxies images, as GitHub does, may show its copy for a while). Markdown:

[![CVE-2026-124278](https://cve.bz/cve/badge/CVE-2026-124278.svg)](https://cve.bz/cve/CVE-2026-124278)

HTML:

<a href="https://cve.bz/cve/CVE-2026-124278"><img src="https://cve.bz/cve/badge/CVE-2026-124278.svg" alt="CVE-2026-124278"></a>

Affected

Versions

From the CNA's record in the CVE List.

ProductAffected
elixir-grpc grpc_serverfrom 1.0.0 before 1.1.0
elixir-grpc grpcfrom 0.8.0 before 1.0.0

Fix and patched versions

  • grpc_server (Hex): fixed in 1.1.0
  • grpc (Hex): fixed in 1.0.0

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
EEF-CVE-2026-124278Hexgrpc_server>=1.0.0 <1.1.01.1.0
EEF-CVE-2026-124278Hexgrpc>=0.8.0 <1.0.01.0.0
EEF-CVE-2026-124278v1.0.6, v1.0.3, v1.0.0no fix published
EEF-CVE-2026-124278v0.11.2, v0.8.1, v0.8.0no fix published

Attack patterns (CAPEC)

  • CAPEC-34 HTTP Response Splitting Likelihood: Medium · Severity: High
  • CAPEC-105 HTTP Request Splitting Likelihood: Medium · Severity: High
  • CAPEC-273 HTTP Response Smuggling Likelihood: Medium · Severity: High

The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.

References

Check your stackJSON