CVE-2026-72705 Rocq Prover before 9.2.0 Guard Checker Accepts Fixpoint Passed as a Higher-Order Argument
A logic flaw in Rocq Prover's guard checker allows proving False, undermining the system's consistency and trustworthiness for formal verification.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-72705?
CVE-2026-72705 is a medium-severity vulnerability in rocq-prover rocq, published on 24 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
The guard checker in Rocq Prover does not follow recursive calls made through a fixpoint's own arguments. A fixpoint may pass itself as a higher-order argument to a second fixpoint, which then applies it to a value that is not a subterm of the structural argument. Passing the recursive function to a plain definition is rejected because the checker unfolds the definition and observes the call, but passing it to a fixpoint is accepted because higher-order recursive calls through fixpoint arguments are not tracked. This admits a type that is definitionally equal to its own negation, so self-application produces False in purely definitional code, without tactics, axioms, plugins or unsafe flags, and Print Assumptions reports the result as closed under the global context. Fixed in Rocq 9.2.0.
Weakness: CWE-670
Which versions are affected by CVE-2026-72705?
How do I fix CVE-2026-72705?
No fix has been published for CVE-2026-72705 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-72705 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-72705 exists.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-f4rc-7978-q94g.