Rocq-Prover Rocq up to 9.2.0 Guard Checker input validation

Summaryinfo

A vulnerability has been found in Rocq-Prover Rocq up to 9.2.0 and classified as problematic. Impacted is an unknown function of the component Guard Checker. The manipulation leads to input validation. This vulnerability is uniquely identified as CVE-2026-72704. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in Rocq-Prover Rocq up to 9.2.0 and classified as problematic. This issue affects an unknown part of the component Guard Checker. The manipulation with an unknown input leads to a input validation vulnerability. Using CWE to declare the problem leads to CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Impacted is integrity, and availability. The summary by CVE is:

The guard checker in Rocq Prover does not recheck the recursive tree representation of an inductive type parameter after that parameter has been changed by transport. A fixpoint may apply a rewrite along an equality between types to its recursive argument, which the guard checker accepts because the inductive type is preserved, while the recursive tree recorded for the parameter is altered. A second fixpoint that calls the first inherits the altered recursive tree without verification, so a call that is not structurally decreasing is accepted as terminating. The resulting non-terminating definition proves that a natural number equals its own successor and therefore False, from which any proposition follows. The demonstration uses two axioms that follow from univalence and are consistent with the calculus of inductive constructions, so the contradiction comes from the guard check rather than from the assumptions. A fix is proposed but not merged.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-72704 since 08/10/2026. The exploitation is known to be easy. The attack may be initiated remotely. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/24/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• Rocq-Prover

Name

• Rocq

Version

• 9.0
• 9.1
• 9.2.0

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion