# CVE-2026-124279: Streaming request body limit enforced only after an 8 MB read in elixir-grpc grpc_server

Status: published. Published: 2026-11-13. Updated: 2026-11-13.

Allocation of Resources Without Limits or Throttling vulnerability in elixir-grpc grpc_server allows unauthenticated attackers to exhaust server memory via client-streaming or bidirectional-streaming requests.

The streaming read clause of GRPC.Server.Adapters.Cowboy.Handler.info/3 (grpc_server/lib/grpc/server/adapters/cowboy/handler.ex) asks Cowboy for up to 8,000,000 bytes per read and compares the running total with max_body_size only after the read returns. The gRPC length prefix of a message is not checked before the message is buffered. Each stream can therefore buffer up to one full read beyond the configured limit before it is refused, and many concurrent streams exhaust node memory. Releases before 1.0.6 apply no limit to streaming requests at all.

This issue affects grpc_server: from 1.0.0 before 1.1.0.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: EEF) — https://github.com/elixir-grpc/grpc/commit/b1e771d558941b1ed4b6de8b39f6a5375543db01

## Affected products and versions

- elixir-grpc / grpc_server (grpc_server): ≥ 1.0.0; < 1.1.0 (affected, semver). Source: CNA: EEF
- elixir-grpc / grpc_server (elixir-grpc/grpc): ≥ 49e18c3ec6bb9afe2f712caad3dbab5c56a68a00; < b1e771d558941b1ed4b6de8b39f6a5375543db01 (affected, git). Source: CNA: EEF

## Severity and prioritization

- CVSS 4.0: 8.2 (high); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N; source: CNA: EEF

- CVSS 4.0: 8.2 (high); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/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; source: NVD: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-770

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/elixir-grpc/grpc/security/advisories/GHSA-736x-r87j-jhcm (CNA: EEF; vendor-advisory, related)

- https://cna.erlef.org/cves/CVE-2026-124279.html (CNA: EEF; related)

- https://osv.dev/vulnerability/EEF-CVE-2026-124279 (CNA: EEF; related)

- https://github.com/elixir-grpc/grpc/commit/49e18c3ec6bb9afe2f712caad3dbab5c56a68a00 (CNA: EEF; related)

- https://github.com/elixir-grpc/grpc/commit/b1e771d558941b1ed4b6de8b39f6a5375543db01 (CNA: EEF; patch)

- https://cna.erlef.org/cves/CVE-2026-124279.html (6b3ad84c-e1a6-4bf7-a703-f496b71e49db)

- https://github.com/elixir-grpc/grpc/commit/49e18c3ec6bb9afe2f712caad3dbab5c56a68a00 (6b3ad84c-e1a6-4bf7-a703-f496b71e49db)

- https://github.com/elixir-grpc/grpc/commit/b1e771d558941b1ed4b6de8b39f6a5375543db01 (6b3ad84c-e1a6-4bf7-a703-f496b71e49db)

- https://github.com/elixir-grpc/grpc/security/advisories/GHSA-736x-r87j-jhcm (6b3ad84c-e1a6-4bf7-a703-f496b71e49db)

- https://osv.dev/vulnerability/EEF-CVE-2026-124279 (6b3ad84c-e1a6-4bf7-a703-f496b71e49db)

## Provenance

- CNA: EEF: https://www.cve.org/CVERecord?id=CVE-2026-124279; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-124279; retrieved 2026-11-13; source updated 2026-11-13

Revision: e7ddd3d8e68c2d0cb523fe1bc72653be075c50daf8a57c40bca187603a796f43

Canonical: https://y2.dev/cve/CVE-2026-124279

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