# 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.

- **Severity:** Medium 6.8 (`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`)
- **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 available:** No
- **Published:** 24 Aug 2026
- **Updated:** 26 Oct 2026
- **Also known as:** GHSA-f4rc-7978-q94g

## 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 (Always-Incorrect Control Flow Implementation)

## 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:

- CVE-2026-72705 — Rocq Guard Checker Accepts Fixpoint Passed as Higher-Order Argument (github_poc): https://github.com/endrazine/rocq-cve-poc-21683

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72705 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-72705 exists.

Affected product: rocq-prover rocq. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-72705/ (Markdown: https://insights.sbomify.com/CVE-2026-72705/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72705
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72705
- OSV: https://osv.dev/vulnerability/CVE-2026-72705

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72705/
Summaries are generated and may contain mistakes; the official description above is the record.