CVE-2026-63209Integer Overflow or Wraparound and Out-of-bounds Write in compress
Updated under an hour ago ()
Does this affect you?
It affects klauspost compress. Add what you run to find out whether that includes you.
EPSS puts the chance of exploitation in the next 30 days at 0.36%, higher than 28% of scored CVEs.
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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
- 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-190, CWE-787
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- 0.36% (percentile 28)
- Assigned by
- GitHub_M
- NVD analysis
- Deferred
- Record last updated
- Sep 29, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
klauspost compress klauspost:compress (from the name) | before 1.18.7 | CNA record |
References
- https://github.com/klauspost/compress/security/advisories/GHSA-259r-337f-4rfwx-refsource-confirm
- https://github.com/klauspost/compress/commit/539243b8823ee8f03e49969823d57c348c917536x-refsource-misc
- https://github.com/klauspost/compress/releases/tag/v1.18.7x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.