{"id":"CVE-2026-63209","sourceIdentifier":"security-advisories@github.com","published":"2026-09-29T15:17:27.130","lastModified":"2026-09-30T19:57:08.043","vulnStatus":"Deferred","cveTags":[],"descriptions":[{"lang":"en","value":"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."}],"affected":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"klauspost","product":"compress","versions":[{"version":"< 1.18.7","status":"affected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":3.6}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-09-29T16:31:39.668233Z","id":"CVE-2026-63209","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"security-advisories@github.com","type":"Secondary","description":[{"lang":"en","value":"CWE-190"},{"lang":"en","value":"CWE-787"}]}],"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"}]}