CVE-2026-72703 (GCVE-0-2026-72703)

Vulnerability from cvelistv5 – Published: 2026-08-24 20:08 – Updated: 2026-08-24 20:08
VLAI
Title
Rocq Prover 8.20 before 9.2.0 Guard Checker Accepts Non-Terminating Fixpoint via Unchecked Cross-Calls
Summary
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.
CWE
  • CWE-670 - Always-Incorrect Control Flow Implementation
Impacted products
Vendor Product Version CPE status
rocq-prover rocq Affected: 8.20 , < 9.2.0 (custom)
guessed Create a notification for this product.
Date Public
2026-02-28 00:00
Show details on NVD website

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          "type": "finder",
          "value": "Tristan St\u00e9rin"
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        }
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              "description": "Always-Incorrect Control Flow Implementation",
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      "providerMetadata": {
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          "url": "https://github.com/rocq-prover/rocq/pull/21684"
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          "url": "https://github.com/endrazine/rocq-cve-poc-21682"
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        {
          "name": "VulnCheck Advisory: Rocq Prover 8.20 before 9.2.0 Guard Checker Accepts Non-Terminating Fixpoint via Unchecked Cross-Calls",
          "tags": [
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          "url": "https://www.vulncheck.com/advisories/rocq-prover-before-guard-checker-accepts-non-terminating-fixpoint-via-unchecked-cross-calls"
        }
      ],
      "title": "Rocq Prover 8.20 before 9.2.0 Guard Checker Accepts Non-Terminating Fixpoint via Unchecked Cross-Calls",
      "x_generator": {
        "engine": "vulncheck-endgame"
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  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-72703",
    "datePublished": "2026-08-24T20:08:30.607Z",
    "dateReserved": "2026-08-10T13:02:20.829Z",
    "dateUpdated": "2026-08-24T20:08:30.607Z",
    "state": "PUBLISHED"
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  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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    "redhat_vex": {
      "current_release_date": "2026-08-24T21:18:43+00:00",
      "cve": "CVE-2026-72703",
      "id": "CVE-2026-72703",
      "initial_release_date": "2026-08-24T20:08:30.607000+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "rocq: Rocq Prover: Logical Flaw Allows Arbitrary Proof Generation via Unchecked Cross-Calls",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72703.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
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