CVE-2026-11404

Cesanta Mongoose Out-of-Bounds Read in MG_TLS_BUILTIN ClientHello Session ID Parsing

Published Jul 9, 2026 CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed
Description
Cesanta Mongoose before 7.22 contains an out-of-bounds read in the built-in TLS server function mg_tls_server_recv_hello(), which uses an attacker-controlled session_id_len byte from a TLS ClientHello as a buffer index without validating it against the length of received data. A remote, unauthenticated attacker can send a single crafted ClientHello with an oversized session id length to read past the receive buffer, crashing any HTTPS, MQTTS, or WSS service built on MG_TLS_BUILTIN.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Title Cesanta Mongoose before 7.22 Out-of-Bounds Read in MG_TLS_BUILTIN ClientHello Session ID Parsing Cesanta Mongoose Out-of-Bounds Read in MG_TLS_BUILTIN ClientHello Session ID Parsing
References
Type Values Removed Values Added
Title Cesanta Mongoose < 7.22 Out-of-Bounds Read in MG_TLS_BUILTIN ClientHello Session ID Parsing Cesanta Mongoose before 7.22 Out-of-Bounds Read in MG_TLS_BUILTIN ClientHello Session ID Parsing
CPEs cpe:2.3:a:cesanta:mongoose:*:*:*:*:*:*:*:*
Type Values Removed Values Added
First Time appeared Cesanta
Cesanta mongoose
Vendors & Products Cesanta
Cesanta mongoose
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Cesanta Mongoose before 7.22 contains an out-of-bounds read in the built-in TLS server function mg_tls_server_recv_hello(), which uses an attacker-controlled session_id_len byte from a TLS ClientHello as a buffer index without validating it against the length of received data. A remote, unauthenticated attacker can send a single crafted ClientHello with an oversized session id length to read past the receive buffer, crashing any HTTPS, MQTTS, or WSS service built on MG_TLS_BUILTIN.
Title Cesanta Mongoose < 7.22 Out-of-Bounds Read in MG_TLS_BUILTIN ClientHello Session ID Parsing
Weaknesses CWE-125
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 3, 2026, 8:28 PM
Reserved
Jun 5, 2026, 5:46 PM
Status
Deferred
Published
Jul 9, 2026, 4:16 PM
Modified
Nov 3, 2026, 9:17 PM