Bug 2571813 (CVE-2026-123828)

Summary: CVE-2026-123828 nodejs: nodejs: Denial of Service via HTTP/2 Alt-Svc heap buffer overflow
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in Node.js. A remote, unauthenticated attacker can cause a Denial of Service (DoS) by sending a specially crafted request with an oversized header to an application that processes HTTP/2 Alternative Services (Alt-Svc). Due to an off-by-one heap buffer overflow, the application writes one byte past the allocated memory buffer, corrupting process memory and causing the server to crash.
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Description OSIDB Bzimport 2026-11-11 18:21:17 UTC 
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.