CVE-2026-11404
Out-of-bounds read in Mongoose TLS server allows remote crash and memory read.
Is CVE-2026-11404 being exploited?
Not confirmed. CVE-2026-11404 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.61% probability of exploitation in the next 30 days.
How severe is CVE-2026-11404?
CVE-2026-11404 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-11404?
Yes. A fix has been recorded for CVE-2026-11404. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-11404 affect?
CVE-2026-11404 affects Cesanta Mongoose < 7.22, MG_TLS_BUILTIN-based HTTPS servers, MQTTS services using Mongoose, WSS services using Mongoose, and 1 further product or version. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-11404?
Upgrade Mongoose to >=7.22; block/inspect suspicious TLS ClientHello traffic.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote unauthenticated attacker can send a crafted TLS ClientHello to read past the buffer and crash HTTPS/MQTTS/WSS services (memory disclosure + DoS).
Immediate action required
- affected< 7.22
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.