CVE-2026-11404 | Cesanta Mongoose before 7.22 contains an out-of-bounds read … | CVSS 7.5 HIGH

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.

Metadata

CVE ID: CVE-2026-11404
State: PUBLISHED
Assigner: VulnCheck
Reserved: 2026-06-05 17:46 UTC
Published: 2026-07-09 15:13 UTC
Last updated: 2026-07-09 16:09 UTC
Primary CWE: CWE-125
Out-of-bounds Read
Vendor / Product: Cesanta / Mongoose
Sources: cve.org · NVD

Severity & Metrics

7.5 HIGH CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC — CISA Coordinator

Exploitation: none
Automatable: yes
Tech. Impact: partial

Affected products (1)

Vendor	Product	Platform	Versions
Cesanta	Mongoose	—	0 < 7.22

Weakness (CWE)

CWE	Source	Description
CWE-125	cna	Out-of-bounds Read

CVSS scores (2)

Score	Severity	Version	Source	Vector
8.7	HIGH	4.0	cna	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
7.5	HIGH	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References (4)

Mongoose 7.22 Release Notes https://github.com/cesanta/mongoose/releases/tag/7.22
Product https://github.com/cesanta/mongoose
Patch Commit https://github.com/cesanta/mongoose/commit/c288ac1f38424ffdd4d2fd5e1893fd4962642db3
https://www.vulncheck.com/advisories/cesanta-mongoose-out-of-bounds-read-in-mg-tls-builtin-clienthello-session-id-parsing