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.
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Wed, 11 Nov 2026 18:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | Node.js is vulnerable to a heap buffer overflow in HTTP/2 session.altsvc() via a long origin | |
| Weaknesses | CWE-122 | |
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cvssV3_0
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Status: PUBLISHED
Assigner: openjs
Published:
Updated: 2026-11-11T18:10:54.030Z
Reserved: 2026-11-06T16:02:55.733Z
Link: CVE-2026-123828
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