Headline
GHSA-794x-2rpg-rfgr: Jujutsu does not have SHA-1 collision detection
Summary
Jujutsu 0.28.0 and earlier rely on versions of gitoxide that use SHA-1 hash implementations without any collision detection, leaving them vulnerable to hash collision attacks.
Details
This is a result of the underlying CVE-2025-31130 / GHSA-2frx-2596-x5r6 vulnerability in the gitoxide library Jujutsu uses to interact with Git repositories; see that advisory for technical details. This separate advisory is being issued due to the downstream impact on users of Jujutsu.
Impact
An attacker with the ability to mount a collision attack on SHA-1 like the SHAttered or SHA-1 is a Shambles attacks could create two distinct Git objects with the same hash. This is becoming increasingly affordable for well‐resourced attackers, with the Shambles researchers in 2020 estimating $45k for a chosen‐prefix collision or $11k for a classical collision, and projecting less than $10k for a chosen‐prefix collision by 2025. The result could be used to disguise malicious repository contents, or potentially exploit assumptions in Jujutsu’s logic to cause further vulnerabilities.
Summary
Jujutsu 0.28.0 and earlier rely on versions of gitoxide that use SHA-1 hash implementations without any collision detection, leaving them vulnerable to hash collision attacks.
Details
This is a result of the underlying CVE-2025-31130 / GHSA-2frx-2596-x5r6 vulnerability in the gitoxide library Jujutsu uses to interact with Git repositories; see that advisory for technical details. This separate advisory is being issued due to the downstream impact on users of Jujutsu.
Impact
An attacker with the ability to mount a collision attack on SHA-1 like the SHAttered or SHA-1 is a Shambles attacks could create two distinct Git objects with the same hash. This is becoming increasingly affordable for well‐resourced attackers, with the Shambles researchers in 2020 estimating $45k for a chosen‐prefix collision or $11k for a classical collision, and projecting less than $10k for a chosen‐prefix collision by 2025. The result could be used to disguise malicious repository contents, or potentially exploit assumptions in Jujutsu’s logic to cause further vulnerabilities.
References
- GHSA-794x-2rpg-rfgr
- jj-vcs/jj@350da7d