Vulnerability · Published Aug 24, 2026 · Assigned by VulnCheck
CVE-2020-37268Coq and Rocq Prover Print Assumptions Omits Unsafe Universe Checking Inlined Through Parameter Inline
Medium 6.3
In plain English
A medium-severity security flaw in rocq from rocq-prover. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.
Official description
Print Assumptions does not report that a definition was produced while universe checking was disabled when that definition reaches the caller through Parameter Inline in a module type. Applying a functor inlines the body of the parameter, and the inlining drops the record that the term was built under Unset Universe Checking, so the resulting constant carries no trace of the unsafe operation. A module implementation can therefore prove False using a universe inconsistency, expose it through an inlined parameter, and have Print Assumptions report the dependent proof as closed under the global context. Because Print Assumptions is the in-process audit used to confirm that a development rests on no unexpected assumptions, a dependency built this way passes that audit while proving arbitrary propositions. The standalone checker coqchk does reject the resulting compiled file. The project records this in dev/doc/critical-bugs.md under non-fixed bugs and rates the risk as moderate when coqchk is not used.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| rocq-prover | rocq | 8.11 – through 9.2.0 |
Weakness: CWE-778 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N
References
- https://github.com/rocq-prover/rocq product
- https://github.com/rocq-prover/rocq/issues/12155 issue-tracking
- https://github.com/rocq-prover/rocq/blob/master/dev/doc/critical-bugs.md technical-description
- https://github.com/endrazine/rocq-cve-poc-12155 exploit
- VulnCheck Advisory: Coq and Rocq Prover Print Assumptions Omits Unsafe Universe Checking Inlined Through Parameter Inline third-party-advisory
- http://www.openwall.com/lists/oss-security/2026/10/26/8