Medium 6.5Published Aug 20, 2026

CVE-2026-73258Mongoose: Multipart boundary/header scan logic error in mg_http_next_multipart

Updated under an hour ago (2026-10-19 06:10 UTC)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for cesanta mongoose

Exploited in the last 30 days

Mongoose is an embedded web server and network library. Prior to 7.22, a remote attacker can place a lone carriage return or line feed in multipart input processed by mg_http_next_multipart() in src/http.c. The loops comparing s[b] and s[b + 1], and s[h2] and s[h2 + 1], use an incorrect AND condition and stop when either character resembles part of a CRLF terminator. This truncates headers, filenames, or boundaries and can cause an application to accept dangerous content after seeing a misleading Content-Type value. This issue is fixed in version 7.22.

CVSS: 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness (CWE): CWE-697
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Aug 20, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

cesanta mongoose cesanta:mongoose (from the name)	before 7.22	CNA record
cesanta mongoose cesanta:mongoose	before 7.22	NVD

References

https://github.com/cesanta/mongoose/security/advisories/GHSA-cc55-8v3r-59p8x-refsource-confirm, exploit, vendor-advisory
https://github.com/cesanta/mongoose/pull/3611x-refsource-misc, issue-tracking, patch
https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71x-refsource-misc, patch
https://github.com/cesanta/mongoose/releases/tag/7.22x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.