Hex release-age cooldown is lifted package-wide when the locked release is retired

Summary

Protection Mechanism Failure vulnerability in hexpm hex allows the owner of a package, or an attacker who has taken over the owner's account, to get a newly published release past the release-age cooldown. The cooldown (cooldown config, HEX_COOLDOWN) withholds versions younger than the configured age during dependency resolution. When the release of a package locked in mix.lock is retired or has a security advisory, Hex.RemoteConverger.build_cooldown_bypass/3 and Hex.RemoteConverger.unsafe_lock_bypass/1 lift the cooldown for every version of that package and of every package the locked release depends on, so that mix deps.update can move off the unsafe release. Retiring a release needs the same package owner permission as publishing one. An attacker who publishes a malicious release can retire the currently locked release, and the next mix deps.update that unlocks the package selects the new release regardless of its age. Hex.Registry.Cooldown.versions/2 checks the bypass by package name alone, so the bypass also covers packages with the same name in other repositories. Cooldown configured through an organization dependency policy is not affected. This issue affects hex: from 2.5.0 before 2.5.2.

Timeline

1. Oct 12, 2026, 3:31 PM UTCCVE published
2. Oct 16, 2026, 5:37 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 16, 2026, 5:38 PM UTCRecord last updated

Affected versions

• hex

  From 2.5.0 · fixed in 2.5.2

• hexpm/hex

  From b4e665d46be8a5f81e8cbbe4c3a67058a19cf133 · fixed in *

References 6