{"id":"CVE-2026-3549","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-3549","generatedAt":"2026-10-28T03:23:03.088Z","title":"Heap Overflow in TLS 1.3 ECH parsing.","description":"Heap Overflow in TLS 1.3 ECH parsing. An integer underflow existed in ECH extension parsing logic when calculating a buffer length, which resulted in writing beyond the bounds of an allocated buffer. Note that in wolfSSL, ECH is off by default, and the ECH standard is still evolving.","published":"2026-03-19T21:17:13.000Z","lastModified":"2026-06-17T10:43:46.000Z","status":"Analyzed","sourceIdentifier":"facts@wolfssl.com","cvss":{"version":"4.0","score":8.3,"severity":"HIGH","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-122"],"affected":["wolfssl/wolfssl"],"epss":{"score":0.00496,"percentile":0.42254,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.50%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://github.com/wolfSSL/wolfssl/pull/9817","tags":["Issue Tracking","Patch"],"source":"facts@wolfssl.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-3549","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}