{"id":"CVE-2026-73252","summary":"Mongoose: Unauthenticated remote heap out-of-bounds read in built-in TLS: off-by-one length check in mg_tls_recv_record() underflows recv_len to SIZE_MAX","details":"Mongoose is an embedded web server and network library. Prior to 7.23, the built-in TLS stack selected by MG_TLS_BUILTIN in src/tls_builtin.c accepts a TLS 1.3 record whose decrypted size is exactly the 16-byte authentication tag with no plaintext or ContentType byte. In mg_tls_recv_record(), the msgsz length check permits that record and the recv_len calculation underflows to SIZE_MAX, so a later handshake step treats stale buffer contents as a trusted message with an effectively unbounded length. An unauthenticated malicious TLS peer can trigger a heap out-of-bounds read before certificate or Finished validation, causing a remote denial of service. This issue is fixed in version 7.23.","aliases":["GHSA-hq58-98f5-2wg3"],"modified":"2026-10-15T10:47:31.568499881Z","published":"2026-10-14T18:24:16.659Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-125","CWE-191"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73252.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73252.json"},{"type":"FIX","url":"https://github.com/cesanta/mongoose/commit/758e301f0c9a9885c1b716195df5fe6d6ac9d53e"},{"type":"WEB","url":"https://github.com/cesanta/mongoose/releases/tag/7.23"},{"type":"ADVISORY","url":"https://github.com/cesanta/mongoose/security/advisories/GHSA-hq58-98f5-2wg3"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73252"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/cesanta/mongoose","events":[{"introduced":"0"},{"fixed":"02bdbb9ed6f0a8f7c42228c6e7cb35d748b60551"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"0"},{"fixed":"7.23"}]}}],"versions":["7.22","7.21","7.20","7.19","7.18","7.17","7.16","7.15","7.14","7.13","7.12","7.11","7.8","7.7","7.6","7.5","7.4","7.3","7.2","7.1","7.0","6.18","6.17","6.16","6.15","6.14","6.13","6.12","6.11","6.10","6.9","6.7","6.6","6.5","6.4","6.3","6.2","6.1","6.0","5.6","5.5_20140120","5.5","5.4","5.3","5.2","5.1","5.0","4.1","4.0","3.8","3.7","3.6","3.5","3.4","3.3","3.2"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-73252.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}