Out-of-bounds Read in Cesanta Mongoose
CVE-2026-73260
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.
Vulnerability class: Buffer Overflow
Published .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Cesanta Mongoose — versions < 7.23
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-73260?
- CVE-2026-73260 is a high-severity vulnerability in Cesanta Mongoose, classified under Out-of-bounds Read. CVSS score: 7.5/10. Published 2026-10-14.
- How severe is CVE-2026-73260?
- High severity. CVSS v3 base score is 7.5 out of 10.