High 7.5Published Oct 14, 2026

CVE-2026-73260Mongoose: Out-of-bounds Read via length-counter underflow in built-in TLS X.509 DER parser

Updated under an hour ago (2026-10-19 07:23 UTC)

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It affects cesanta mongoose. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.23%, higher than 13% of scored CVEs.

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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 7.23, the built-in TLS certificate parser selected by MG_TLS_BUILTIN fails to verify that a long-form DER element length fits within the remaining certificate buffer. In mg_der_to_tlv() and mg_der_next(), a peer-controlled length can advance the parser beyond the certificate and underflow the remaining uint32_t length, causing mg_tls_parse_cert_der() to continue walking an invalid pointer. An unauthenticated malicious TLS server, or a client presenting a certificate to a server configured for client certificates, can trigger an out-of-bounds read and denial of service during the handshake. This issue is fixed in version 7.23.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-125
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.23% (percentile 13)
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Oct 14, 2026
First seen by InfoSec Signals: Oct 14, 2026

Affected products

Affected products

cesanta mongoose cesanta:mongoose (from the name)	before 7.23	CNA record

References

https://github.com/cesanta/mongoose/security/advisories/GHSA-f6wr-mg35-p25gx-refsource-confirm
https://github.com/cesanta/mongoose/commit/a8b4ae95db3c2db85e5ad9db3fefaeebb5f7b43ex-refsource-misc
https://github.com/cesanta/mongoose/releases/tag/7.23x-refsource-misc

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.