{"id":"CVE-2026-25537","state":"PUBLISHED","title":"jsonwebtoken has Type Confusion that leads to potential authorization bypass","description":"jsonwebtoken is a JWT lib in rust. Prior to version 10.3.0, there is a Type Confusion vulnerability in jsonwebtoken, specifically, in its claim validation logic. When a standard claim (such as nbf or exp) is provided with an incorrect JSON type (Like a String instead of a Number), the library’s internal parsing mechanism marks the claim as “FailedToParse”. Crucially, the validation logic treats this “FailedToParse” state identically to “NotPresent”. This means that if a check is enabled (like: validate_nbf = true), but the claim is not explicitly marked as required in required_spec_claims, the library will skip the validation check entirely for the malformed claim, treating it as if it were not there. This allows attackers to bypass critical time-based security restrictions (like “Not Before” checks) and commit potential authentication and authorization bypasses. This issue has been patched in version 10.3.0.","publishedAt":"2026-02-04T21:31:53.511Z","updatedAt":"2026-02-05T20:52:48.021Z","severity":{"score":5.5,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P","source":"GitHub_M"},"assigner":"GitHub_M","products":["Keats jsonwebtoken"],"affected":[{"vendor":"Keats","product":"jsonwebtoken","versions":[{"version":"< 10.3.0","status":"affected"}]}],"references":["https://github.com/Keats/jsonwebtoken/security/advisories/GHSA-h395-gr6q-cpjc","https://github.com/Keats/jsonwebtoken/commit/abbc3076742c4161347bc6b8bf4aa5eb86e1dc01"],"weaknesses":["CWE-843"],"ingestedAt":"2026-10-29T20:11:21.040Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/25xxx/CVE-2026-25537.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-25537","state":"PUBLISHED","datePublished":"2026-02-04T21:31:53.511Z","dateUpdated":"2026-02-05T20:52:48.021Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-02-02T19:59:47.374Z"},"containers":{"cna":{"title":"jsonwebtoken has Type Confusion that leads to potential authorization bypass","descriptions":[{"lang":"en","value":"jsonwebtoken is a JWT lib in rust. Prior to version 10.3.0, there is a Type Confusion vulnerability in jsonwebtoken, specifically, in its claim validation logic. When a standard claim (such as nbf or exp) is provided with an incorrect JSON type (Like a String instead of a Number), the library’s internal parsing mechanism marks the claim as “FailedToParse”. Crucially, the validation logic treats this “FailedToParse” state identically to “NotPresent”. This means that if a check is enabled (like: validate_nbf = true), but the claim is not explicitly marked as required in required_spec_claims, the library will skip the validation check entirely for the malformed claim, treating it as if it were not there. This allows attackers to bypass critical time-based security restrictions (like “Not Before” checks) and commit potential authentication and authorization bypasses. This issue has been patched in version 10.3.0."}],"affected":[{"vendor":"Keats","product":"jsonwebtoken","versions":[{"version":"< 10.3.0","status":"affected"}]}],"references":[{"url":"https://github.com/Keats/jsonwebtoken/security/advisories/GHSA-h395-gr6q-cpjc","name":"https://github.com/Keats/jsonwebtoken/security/advisories/GHSA-h395-gr6q-cpjc","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/Keats/jsonwebtoken/commit/abbc3076742c4161347bc6b8bf4aa5eb86e1dc01","name":"https://github.com/Keats/jsonwebtoken/commit/abbc3076742c4161347bc6b8bf4aa5eb86e1dc01","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":5.5,"baseSeverity":"MEDIUM","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-843","lang":"en","description":"CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-02-04T21:31:53.511Z"},"source":{"advisory":"GHSA-h395-gr6q-cpjc","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/Keats/jsonwebtoken/security/advisories/GHSA-h395-gr6q-cpjc","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-02-05T20:52:41.199183Z","id":"CVE-2026-25537","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-02-05T20:52:48.021Z"}}]}}}