CVE-2026-63209
Integer Overflow or Wraparound and Out-of-bounds Write in compress
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-190 CWE-787 |
| Vendor | klauspost |
| Product | compress |
| Published | Sep 29, 2026 |
| Last Updated | Sep 29, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
klauspost / compress
< 1.18.7