CVE-2026-39831 Affecting ko package, versions <0.18.1-r17
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-CHAINGUARDLATEST-KO-17037174
- published29 May 2026
- disclosed22 May 2026
Introduced: 22 May 2026
NewCVE-2026-39831 (opens in a new tab)How to fix?
Upgrade Chainguard ko to version 0.18.1-r17 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream ko package and not the ko package as distributed by Chainguard.
See How to fix? for Chainguard relevant fixed versions and status.
The Verify() method for FIDO/U2F security key types (sk-ecdsa-sha2-nistp256@openssh.com, sk-ssh-ed25519@openssh.com) did not check the User Presence flag. Signatures generated without physical touch were accepted, allowing unattended use of a hardware security key. To restore the previous behavior, return a "no-touch-required" extension in Permissions.Extensions from PublicKeyCallback.