{"id":"CVE-2026-72705","state":"PUBLISHED","title":"Rocq Prover before 9.2.0 Guard Checker Accepts Fixpoint Passed as a Higher-Order Argument","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.","publishedAt":"2026-08-24T20:08:32.535Z","updatedAt":"2026-10-26T01:23:56.439Z","severity":{"score":6.8,"label":"Medium","version":"4.0","vector":"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","source":"VulnCheck"},"assigner":"VulnCheck","products":["rocq-prover rocq"],"affected":[{"vendor":"rocq-prover","product":"rocq","packageURL":"pkg:github/rocq-prover/rocq","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"9.2.0","versionType":"custom"}],"repo":"https://github.com/rocq-prover/rocq"}],"references":["https://github.com/rocq-prover/rocq","https://github.com/rocq-prover/rocq/issues/21683","https://github.com/rocq-prover/rocq/pull/21684","https://github.com/endrazine/rocq-cve-poc-21683","https://www.vulncheck.com/advisories/rocq-prover-before-guard-checker-accepts-fixpoint-passed-as-a-higher-order-argument","http://www.openwall.com/lists/oss-security/2026/10/26/6"],"weaknesses":["CWE-670"],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72705.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72705","state":"PUBLISHED","datePublished":"2026-08-24T20:08:32.535Z","dateUpdated":"2026-10-26T01:23:56.439Z","assignerShortName":"VulnCheck","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateReserved":"2026-08-10T13:02:52.001Z"},"containers":{"cna":{"title":"Rocq Prover before 9.2.0 Guard Checker Accepts Fixpoint Passed as a Higher-Order Argument","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"rocq-prover","product":"rocq","packageURL":"pkg:github/rocq-prover/rocq","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"9.2.0","versionType":"custom"}],"repo":"https://github.com/rocq-prover/rocq"}],"references":[{"url":"https://github.com/rocq-prover/rocq","tags":["product"]},{"url":"https://github.com/rocq-prover/rocq/issues/21683","tags":["issue-tracking"]},{"url":"https://github.com/rocq-prover/rocq/pull/21684","tags":["issue-tracking","patch"]},{"url":"https://github.com/endrazine/rocq-cve-poc-21683","tags":["exploit"]},{"url":"https://www.vulncheck.com/advisories/rocq-prover-before-guard-checker-accepts-fixpoint-passed-as-a-higher-order-argument","name":"VulnCheck Advisory: Rocq Prover before 9.2.0 Guard Checker Accepts Fixpoint Passed as a Higher-Order Argument","tags":["third-party-advisory"]}],"metrics":[{"format":"CVSS","cvssV4_0":{"version":"4.0","vectorString":"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","baseScore":6.8,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE"}},{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N","baseScore":6.3,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"CHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"NONE"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-670","lang":"en","description":"Always-Incorrect Control Flow Implementation","type":"CWE"}]}],"providerMetadata":{"shortName":"VulnCheck","orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateUpdated":"2026-09-24T14:18:52.758Z"},"datePublic":"2026-02-28T00:00:00.000Z","credits":[{"lang":"en","value":"Tristan Stérin","type":"finder"},{"lang":"en","value":"Jonathan Brossard (MOABI)","type":"finder"}],"x_generator":{"engine":"vulncheck-endgame"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-26T15:46:51.503814Z","id":"CVE-2026-72705","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-26T16:13:14.137Z"}},{"title":"CVE Program Container","references":[{"url":"http://www.openwall.com/lists/oss-security/2026/10/26/6"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2026-10-26T01:23:56.439Z"}}]}}}