CVE-2026-105668: Hex release-age cooldown is lifted package-wide when the locked release is retired
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, HEXCOOLDOWN) 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.buildcooldownbypass/3 and Hex.RemoteConverger.unsafelockbypass/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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
hexto a version that resolves this vulnerability.Fixed in 2.5.2
Event History
Frequently Asked Questions
Who is exposed to this issue?
Users of Hex release-age cooldown configured through the cooldown config or HEX_COOLDOWN are exposed when updating dependencies. Organization dependency-policy cooldown configuration is not affected.
What does an attacker need to bypass the cooldown?
The attacker must be able to publish and retire releases for the targeted package, either as the package owner or by compromising the owner’s account. They can publish a malicious release, retire the release pinned in mix.lock, and wait for a user to run mix deps.update.
When does the malicious release become eligible for selection?
The bypass occurs when the locked release is retired or has a security advisory and mix deps.update unlocks the package to move away from that release. The cooldown is then lifted for all versions of that package, regardless of release age.
Can the bypass affect packages in another repository?
Yes. The cooldown bypass is checked by package name alone, so it can also cover packages with the same name in other repositories.
What can be done if patching is not immediately possible?
Use an organization dependency-policy cooldown where available, since that configuration is not affected. Avoid running mix deps.update automatically or without reviewing dependency changes when a locked package release has been retired or flagged by a security advisory.