Rocq Prover 8.20 before 9.2.0 Guard Checker Accepts Non-Terminating Fixpoint via Unchecked Cross-Calls
Summary
| CVE | CVE-2026-72703 |
|---|---|
| State | PUBLISHED |
| Assigner | VulnCheck |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-24 20:17:18 UTC |
| Updated | 2026-08-24 20:17:18 UTC |
| Description | The guard checker in Rocq Prover treats a parameter of a nested mutual fixpoint as uniform without examining calls between the different bodies of that fixpoint. find_uniform_parameters in kernel/inductive.ml inspects only self-recursive calls, so when no body calls itself the function concludes that every parameter is uniform. A parameter that grows through a cross-call from one body to another therefore keeps the subterm specification it inherited from the enclosing fixpoint, and a recursive call guarded by that specification is accepted although the argument is not structurally smaller. A non-terminating definition is admitted as structurally decreasing, which yields a term whose value equals its own successor and so a proof of False, from which any proposition follows. The proof requires no axioms, plugins or unsafe flags and Print Assumptions reports it as closed under the global context. Introduced in Coq 8.20 and fixed in Rocq 9.2.0. |
Risk And Classification
Primary CVSS: v4.0 6.8 MEDIUM from [email protected]
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Problem Types: CWE-670 | CWE-670 Always-Incorrect Control Flow Implementation
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 6.8 | MEDIUM | CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 6.8 | MEDIUM | CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N |
| 3.1 | [email protected] | Primary | 6.3 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N |
| 3.1 | CNA | CVSS | 6.3 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N |
CVSS v4.0 Breakdown
Attack Vector
LocalAttack Complexity
LowAttack Requirements
NonePrivileges Required
NoneUser Interaction
PassiveConfidentiality
NoneIntegrity
HighAvailability
NoneSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
Attack Vector
LocalAttack Complexity
LowPrivileges Required
NoneUser Interaction
RequiredScope
ChangedConfidentiality
NoneIntegrity
HighAvailability
NoneCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Rocq-prover | Rocq | affected 8.20 9.2.0 custom | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| www.vulncheck.com/advisories/rocq-prover-before-guard-checker-accepts-non-termi... | [email protected] | www.vulncheck.com | |
| github.com/rocq-prover/rocq | [email protected] | github.com | |
| github.com/endrazine/rocq-cve-poc-21682 | [email protected] | github.com | |
| github.com/rocq-prover/rocq/pull/21684 | [email protected] | github.com | |
| github.com/rocq-prover/rocq/issues/21682 | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Tristan Stérin (en)
CNA: Jonathan Brossard (MOABI) (en)
There are currently no legacy QID mappings associated with this CVE.