high7.5
CVE-2026-63209
Compress/s2: Integer Overflow or Wraparound and Out-of-bounds Write in compress
Impact
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 packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/klauspost/compress | <= 1.18.6 | 1.18.7 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-259r-337f-4rfw
- https://github.com/klauspost/compress/security/advisories/GHSA-259r-337f-4rfw
- https://nvd.nist.gov/vuln/detail/CVE-2026-63209
- https://github.com/klauspost/compress/pull/1163
- https://github.com/klauspost/compress/commit/539243b8823ee8f03e49969823d57c348c917536
- https://github.com/klauspost/compress/commit/8668e357e776d5152ed62f33c17f21b8690664fa
- https://github.com/klauspost/compress/releases/tag/v1.18.7