An integer overflow vulnerability exists in the WebSocket component of Mongoose 7.5 thru 7.17.

published 2025-09-29 13 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-31586

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits: 0; none known

An integer overflow vulnerability exists in the WebSocket component of Mongoose 7.5 thru 7.17. By sending a specially crafted WebSocket request, an attacker can cause the application to crash. If downstream vendors integrate this component improperly, the issue may lead to a buffer overflow.

Patch / fix

distros 1 links 1

swupdate Debian 14 2025.12+dfsg-1

debian advisories DEBIAN-CVE-2025-51495

github.com/cesanta/mongoose#3131 pull request

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-2025-51495 updated 2026-06-28 cvss 7.5

mongoose: Integer Overflow in Mongoose's WebSocket component

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

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

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 13 mo ago (2025-09-29)

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/cainiao159357/CVE-2025-51495 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Classification

Weakness

CWE-190 Integer Overflow or Wraparound

References

github.com /cesanta/mongoose/pull/3131
issue-tracking, patch
github.com /cainiao159357/CVE-2025-51495
exploit
github.com /cesanta/mongoose
product

Sources

CVE List CVE-2025-51495
NVD CVE-2025-51495

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary