# CVE-2026-72704: Rocq Prover through 9.2.0 Guard Checker Trusts Corrupted Recursive Tree After Transport

> Attackers can exploit a guard checker flaw in Rocq Prover to prove False, enabling arbitrary code execution or logical contradictions in verified software.

- **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-h294-vvmw-mqg3

## What is CVE-2026-72704?

CVE-2026-72704 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 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.

Weakness: CWE-670 (Always-Incorrect Control Flow Implementation)

## Which versions are affected by CVE-2026-72704?


## How do I fix CVE-2026-72704?

No fix has been published for CVE-2026-72704 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-72704 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-72704 exists.

Public exploit code:

- CVE-2026-72704 — Rocq Guard Checker Trusts Corrupted Recursive Tree After Transport (github_poc): https://github.com/endrazine/rocq-cve-poc-22024

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72704 and fix it if it is affected.

What it is: CVE-2026-72704 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-2026-72704 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-2026-72704/ (Markdown: https://insights.sbomify.com/CVE-2026-72704/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72704
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72704
- OSV: https://osv.dev/vulnerability/CVE-2026-72704

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72704/
Summaries are generated and may contain mistakes; the official description above is the record.