CVE-2026-119236
CVE-2026-119236
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.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| mvfst |
≥ v0.0.0.0; < v2026.11.09.00 (affected, semver)
Other versions: unaffected |
CNA: Meta |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
No CVSS assessment reported. An unscored record is not a low-severity determination.
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://www.facebook.com/security/advisories/cve-2026-119236CNA: Meta · x_refsource_CONFIRM
- https://github.com/meta/mvfst/commit/7e5cff58e8cbed87793141ceeca0a8a343c67c44CNA: Meta · x_refsource_MISC
- https://github.com/meta/mvfst/commit/7e5cff58e8cbed87793141ceeca0a8a343c67c44[email protected]
- https://www.facebook.com/security/advisories/cve-2026-119236[email protected]
For agents and automation
Read public disclosures for free as Markdown or JSON. Compatible browsers also expose native WebMCP tools to search disclosures, read this page, and discover API access.
Use the ontology-linked Cyber API with x402 pay per request, or a Y2 Pro or Elite API key with the intel:cyber scope.
Endpoints and access details
https://api.y2.dev/api/v2/cyber/cveshttps://api.y2.dev/api/v2/cyber/cves/{cveId}
A workspace owner or admin can create a Pro or Elite API key. Send Authorization: Bearer <Y2_API_KEY> from your trusted agent runtime.
For x402, omit Authorization and read the HTTP 402 payment challenge before signing a retry. Public browser tools do not make payments.