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Fencer Intel
medium 5.9

CVE-2026-123828 json

Node.js is vulnerable to a heap buffer overflow in HTTP/2 session.altsvc() via a long origin

published 16h ago modified 15h ago also EUVD-2026-123669

cvss
5.9
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
—
no EPSS score yet
public exploits
0
none known

Summary

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.

Patch / fix

  • nodejs node 24.22.3, 26.13.1
  • nodejs Alpine 3.22, Alpine 3.21 22.23.5-r0
  • nodejs Alpine 3.24, Alpine 3.23 24.22.3-r0

alpine advisories ALPINE-CVE-2026-123828

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-123828 updated cvss 5.9

nodejs: nodejs: Denial of Service via HTTP/2 Alt-Svc heap buffer overflow

  • Red Hat Hardened Images nodejs25 25.9.0-1.7.hum1, nodejs20 20.20.2-1.3.hum1, nodejs24 24.22.2-0.2.hum1, nodejs26 26.13.0-0.1.1.hum1, nodejs22 22.23.4-2.3.2.3.1.hum1
    affected: workaround, no fix available, no fix planned “Will not fix”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CVSS scores

assigned by version score vector
CNA 3.0 5.9 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • nodejs node

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow
Technology feeds

References

Sources

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