{"id":"CVE-2026-63209","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-63209","generatedAt":"2026-10-28T00:53:34.767Z","title":"Prior to version 1.18.7, a signed integer overflow vulnerability in s2.NewDict() allows an attacker to bypass repeat index validation by supplying a dictionary with a uvarint-encoded repeat value exceeding MaxInt64.","description":"compress provides various compression algorithms. Prior to version 1.18.7, a signed integer overflow vulnerability in s2.NewDict() allows an attacker to bypass repeat index validation by supplying a dictionary with a uvarint-encoded repeat value exceeding MaxInt64. When Dict.Encode() is subsequently called, the overflowed negative repeat value causes an out-of-bounds memory access via unsafe.Pointer arithmetic, crashing the process with SIGSEGV. This issue has been patched in version 1.18.7.","published":"2026-09-29T15:17:27.000Z","lastModified":"2026-09-30T19:57:08.000Z","status":"Deferred","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-190","CWE-787"],"affected":[],"epss":{"score":0.00501,"percentile":0.4262,"date":"2026-10-26","history":[{"date":"2026-09-30","score":0.00365,"percentile":0.27875}]},"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":[{"kind":"new","label":"New CVE","at":"2026-09-29T15:17:27.000Z","detail":{"score":"7.5","severity":"HIGH","publishedAt":"2026-09-29T15:17:27.130Z"},"summary":"New CVE, high severity (CVSS 7.5)."}],"references":[{"url":"https://github.com/klauspost/compress/commit/539243b8823ee8f03e49969823d57c348c917536","source":"security-advisories@github.com"},{"url":"https://github.com/klauspost/compress/releases/tag/v1.18.7","source":"security-advisories@github.com"},{"url":"https://github.com/klauspost/compress/security/advisories/GHSA-259r-337f-4rfw","source":"security-advisories@github.com"},{"url":"https://github.com/klauspost/compress/security/advisories/GHSA-259r-337f-4rfw","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-63209","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."}