# CVE-2026-72704: Rocq Prover guard checker rectree corruption

Source: https://junglewise.ai/threats/cve-2026-72704-rocq-prover-guard-checker-rectree-corruption  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-24. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-72704 · Severity: medium · CVSS 6.3 · Published 2026-08-24

Rocq Prover is an interactive theorem prover used for formal verification of mathematical proofs and software correctness. A flaw in its guard checker (which validates that recursive functions terminate) allows attackers to prove false statements by corrupting the internal recursion tracking mechanism. An exploit can demonstrate that 0 equals 1, undermining the logical soundness of any formal proof that relies on this component.

## Quick answers

**Is CVE-2026-72704 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-72704 being exploited in the wild.

**How severe is CVE-2026-72704?** Medium severity, with a CVSS score of 6.3, published 24 August 2026.

**Which products and versions are affected?** Rocq Prover Project Rocq Prover ≤ 9.2.0.

**Is there a fix for CVE-2026-72704?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-72704 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-72704?** Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The guard checker in Rocq Prover fails to recheck the rectree (recursion tree representation) of inductive type parameters after they are modified through transport operations (type rewrites). A fixpoint can silently corrupt the rectree by applying a rewrite to its recursive argument; when a second fixpoint calls the first, it inherits the corrupted rectree without re-verification, leading the guard checker to incorrectly accept non-terminating definitions as structurally decreasing. The exploit uses two axioms consistent with univalence and the calculus of inductive constructions, then constructs a non-terminating function that produces the contradiction 0=1. The root cause is CWE-670 (control flow implementation error), and no public patch has been merged as of the advisory date.

## Affected products

- Rocq Prover Project Rocq Prover ≤ 9.2.0

## Timeline

- 2026-08-24: disclosed
- 2026-08-24: advisory

## References

- [https://github.com/endrazine/rocq-cve-poc-22024](https://github.com/endrazine/rocq-cve-poc-22024)
- [https://github.com/rocq-prover/rocq](https://github.com/rocq-prover/rocq)