Bug 2498552 (CVE-2026-11404)

Summary: CVE-2026-11404 mongoose: Mongoose: Denial of Service via out-of-bounds read in TLS server
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Mongoose. An out-of-bounds read vulnerability exists in the built-in TLS server function mg_tls_server_recv_hello(). A remote, unauthenticated attacker can exploit this by sending a specially crafted TLS ClientHello message with an oversized session ID length. This can lead to reading past the receive buffer, causing a denial of service (DoS) by crashing any HTTPS, MQTTS, or WSS service utilizing MG_TLS_BUILTIN.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2511540, 2511541, 2511542, 2511544    
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Description OSIDB Bzimport 2026-07-09 16:02:13 UTC 
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.