CVE-2026-63209

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.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/klauspost/compress/commit/539243b8823ee8f03e49969823d57c348c917536
https://github.com/klauspost/compress/releases/tag/v1.18.7
https://github.com/klauspost/compress/security/advisories/GHSA-259r-337f-4rfw
https://github.com/klauspost/compress/security/advisories/GHSA-259r-337f-4rfw

Configurations

No configuration.

History

29 Sep 2026, 17:17

Type	Values Removed	Values Added
References	~~() https://github.com/klauspost/compress/security/advisories/GHSA-259r-337f-4rfw -~~	() https://github.com/klauspost/compress/security/advisories/GHSA-259r-337f-4rfw -

29 Sep 2026, 15:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-09-29 15:17

Updated : 2026-09-30 19:57

NVD link : CVE-2026-63209

Mitre link : CVE-2026-63209

CVE.ORG link : CVE-2026-63209

JSON object : View

Products Affected

No product.

CWE

CWE-190

Integer Overflow or Wraparound

CWE-787

Out-of-bounds Write

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