{"id":"CVE-2026-63209","summary":"Integer Overflow or Wraparound and Out-of-bounds Write in compress","details":"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.","aliases":["GHSA-259r-337f-4rfw","GO-2026-5841"],"modified":"2026-09-30T03:55:34.839663968Z","published":"2026-09-29T14:58:53.366Z","database_specific":{"cwe_ids":["CWE-190","CWE-787"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63209.json","cna_assigner":"GitHub_M"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63209.json"},{"type":"FIX","url":"https://github.com/klauspost/compress/commit/539243b8823ee8f03e49969823d57c348c917536"},{"type":"WEB","url":"https://github.com/klauspost/compress/releases/tag/v1.18.7"},{"type":"ADVISORY","url":"https://github.com/klauspost/compress/security/advisories/GHSA-259r-337f-4rfw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63209"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/klauspost/compress","events":[{"introduced":"0"},{"fixed":"8668e357e776d5152ed62f33c17f21b8690664fa"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"0"},{"fixed":"1.18.7"}]}}],"versions":["v1.18.6","v1.18.5","v1.18.4","v1.18.2","v1.18.1","v1.18.0","v1.17.11","v1.17.10","v1.17.9","v1.17.8","v1.17.7","v1.17.6","v1.17.5","v1.17.4","v1.17.3","v1.17.2","v1.17.1","v1.17.0","v1.16.7","v1.16.6","v1.16.5","v1.16.4","v1.16.3","v1.16.2","v1.16.1","v1.16.0","v1.15.15","v1.15.14","v1.15.13","v1.15.12","v1.15.11","v1.15.10","v1.15.9","v1.15.8","v1.15.7","v1.15.6","v1.15.5","v1.15.4","v1.15.3","v1.15.2","v1.15.1","v1.15.0","v1.14.4","v1.14.3","v1.14.2","v1.14.1","v1.14.0","v1.13.6","v1.13.5","v1.13.4","v1.13.3","v1.13.2","v1.13.1","v1.13.0","v1.12.3","v1.12.2","v1.12.1","v1.11.13","v1.11.12","v1.11.11","v1.11.10","v1.11.9","v1.11.8","v1.11.7","v1.11.6","v1.11.5","v1.11.4","v1.11.3","v1.11.2","v1.11.1","v1.11.0","v1.10.11","v1.10.10","v1.10.9","v1.10.8","v1.10.7","v1.10.6","v1.10.5","v1.10.4","v1.10.3","v1.10.2","v1.10.1","v1.10.0","v1.9.8","v1.9.7","v1.9.6","v1.9.5","v1.9.4","v1.9.3","v1.9.2","v1.9.1","v1.9.0","v1.8.6","v1.8.5","v1.8.4","v1.8.3","v1.8.2","v1.8.1","v1.8.0","v1.7.6","v1.7.5","v1.7.4","v1.7.3","v1.7.2","v1.7.1","v1.7.0","v1.6.2","v1.6.1","v1.6.0","v1.5.0","v1.4.1","v1.4.0","v1.3.0","v1.2.1","v1.2","v1.1","v1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63209.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"}]}