CVE-2026-123828
Node.js is vulnerable to a heap buffer overflow in HTTP/2 session.altsvc() via a long origin
A one-byte heap buffer overflow in Node.js HTTP/2 Alt-Svc handling lets a remote, unauthenticated attacker corrupt process memory. When an application passes an attacker-controlled value such as a request's :authority header to Http2Session.altsvc(), the AltSvc implementation in src/node_http2.cc allocates a buffer sized to the origin length and then writes it with a null terminator, placing one byte past the end of the allocation. A single request carrying a long but syntactically valid :authority triggers the out-of-bounds write, which aborts the process and serves as a remote heap-corruption primitive. This vulnerability affects Node.js 26.x and 24.x.
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 |
|---|---|---|
| node nodejs |
≥ 24.0.0; < 24.22.3 (affected, semver) ≥ 25.0.0; < 26.13.1 (affected, semver) Other versions: unaffected |
CNA: openjs |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.0 / 5.9 medium |
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H | CNA: openjs |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://nodejs.org/en/blog/vulnerability/november-2026-security-releasesCNA: openjs · vendor-advisory
- https://cna.openjsf.org/security-advisories.htmlCNA: openjs
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