{"id":"CVE-2026-54911","state":"PUBLISHED","title":"UltraJSON: Malformed/Truncated UTF-8 Accepted and Silently Rewritten in ujson.dumps()","description":"UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Prior to 5.13.0, ujson.dumps() (or ujson.dump() or ujson.encode()) have a reject_bytes=False option. When set, they may accept malformed or truncated UTF-8 byte sequences, silently rewriting them into different Unicode characters instead of rejecting them. This leads to input validation bypass and data integrity issues. This vulnerability is fixed in 5.13.0.","publishedAt":"2026-06-22T20:53:07.019Z","updatedAt":"2026-06-23T14:20:13.488Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["ultrajson ultrajson"],"affected":[{"vendor":"ultrajson","product":"ultrajson","versions":[{"version":"< 5.13.0","status":"affected"}]}],"references":["https://github.com/ultrajson/ultrajson/security/advisories/GHSA-3j69-69wj-xqx2","https://github.com/ultrajson/ultrajson/commit/169eaf36b1116fece5034ee79a7a0ef3f6deedcf","https://github.com/ultrajson/ultrajson/releases/tag/5.13.0"],"weaknesses":["CWE-20"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/54xxx/CVE-2026-54911.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-54911","state":"PUBLISHED","datePublished":"2026-06-22T20:53:07.019Z","dateUpdated":"2026-06-23T14:20:13.488Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-16T13:49:33.556Z"},"containers":{"cna":{"title":"UltraJSON: Malformed/Truncated UTF-8 Accepted and Silently Rewritten in ujson.dumps()","descriptions":[{"lang":"en","value":"UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Prior to 5.13.0, ujson.dumps() (or ujson.dump() or ujson.encode()) have a reject_bytes=False option. When set, they may accept malformed or truncated UTF-8 byte sequences, silently rewriting them into different Unicode characters instead of rejecting them. This leads to input validation bypass and data integrity issues. This vulnerability is fixed in 5.13.0."}],"affected":[{"vendor":"ultrajson","product":"ultrajson","versions":[{"version":"< 5.13.0","status":"affected"}]}],"references":[{"url":"https://github.com/ultrajson/ultrajson/security/advisories/GHSA-3j69-69wj-xqx2","name":"https://github.com/ultrajson/ultrajson/security/advisories/GHSA-3j69-69wj-xqx2","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/ultrajson/ultrajson/commit/169eaf36b1116fece5034ee79a7a0ef3f6deedcf","name":"https://github.com/ultrajson/ultrajson/commit/169eaf36b1116fece5034ee79a7a0ef3f6deedcf","tags":["x_refsource_MISC"]},{"url":"https://github.com/ultrajson/ultrajson/releases/tag/5.13.0","name":"https://github.com/ultrajson/ultrajson/releases/tag/5.13.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-20","lang":"en","description":"CWE-20: Improper Input Validation","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-06-22T20:53:07.019Z"},"source":{"advisory":"GHSA-3j69-69wj-xqx2","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-23T14:19:57.855154Z","id":"CVE-2026-54911","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-23T14:20:13.488Z"}}]}}}