# CVE-2026-119236: CVE-2026-119236

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

An mvfst QUIC server retained CRYPTO frame data received at an encryption level (Initial or Handshake) that the TLS handshake had already moved past. Because the transport treated this data as delivered, it did not count against the CRYPTO stream buffer limit. A remote, unauthenticated client could complete a handshake, withhold its acknowledgment of the server's HANDSHAKE_DONE frame so that Handshake keys stay in use, and keep sending Handshake-level CRYPTO data at increasing offsets, causing unbounded memory growth on the server and leading to denial of service. This issue affects mvfst versions prior to v2026.11.09.00.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Facebook / mvfst: ≥ v0.0.0.0; < v2026.11.09.00 (affected, semver). Source: CNA: Meta

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-770

## Exploit evidence

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

## References

- https://www.facebook.com/security/advisories/cve-2026-119236 (CNA: Meta; x_refsource_CONFIRM)

- https://github.com/meta/mvfst/commit/7e5cff58e8cbed87793141ceeca0a8a343c67c44 (CNA: Meta; x_refsource_MISC)

- https://github.com/meta/mvfst/commit/7e5cff58e8cbed87793141ceeca0a8a343c67c44 (cve-assign@fb.com)

- https://www.facebook.com/security/advisories/cve-2026-119236 (cve-assign@fb.com)

## Provenance

- CNA: Meta: https://www.cve.org/CVERecord?id=CVE-2026-119236; retrieved 2026-11-11; source updated 2026-11-11

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-119236; retrieved 2026-11-11; source updated 2026-11-11

Revision: 6fe7b621e84067be9b7e77b6bc6390941f8a3165cba766b9362109663a9dc8af

Canonical: https://y2.dev/cve/CVE-2026-119236

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