{"id":"CVE-2026-77528","state":"PUBLISHED","title":"Autobahn Python permessage-deflate bypasses maxMessagePayloadSize after inflation","description":"Autobahn Python is a WebSocket and WAMP implementation for Python that supports Twisted and asyncio. Prior to 26.7.1, WebSocket endpoints that accept permessage-deflate and rely on maxMessagePayloadSize enforce that limit against the compressed frame length before inflation but do not recheck the decompressed message size before delivery. A remote unauthenticated client can send a valid compressed frame below the configured wire-size limit that expands beyond the application message limit, causing oversized data to be allocated, joined, validated, and passed to application callbacks. This can create resource-exhaustion pressure, but the advisory does not establish confidentiality or integrity impact. This issue is fixed in version 26.7.1.","publishedAt":"2026-09-18T19:42:18.767Z","updatedAt":"2026-09-19T14:11:38.071Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","source":"GitHub_M"},"assigner":"GitHub_M","products":["crossbario autobahn-python"],"affected":[{"vendor":"crossbario","product":"autobahn-python","versions":[{"version":"< 26.7.1","status":"affected"}]}],"references":["https://github.com/crossbario/autobahn-python/security/advisories/GHSA-hxp9-w8x3-p566","https://github.com/crossbario/autobahn-python/pull/1916","https://github.com/crossbario/autobahn-python/commit/77d323a30b09b1828ad8be2ce6344e056970e613","https://github.com/crossbario/autobahn-python/releases/tag/v26_7_1"],"weaknesses":["CWE-409","CWE-770"],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/77xxx/CVE-2026-77528.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-77528","state":"PUBLISHED","datePublished":"2026-09-18T19:42:18.767Z","dateUpdated":"2026-09-19T14:11:38.071Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-08-20T20:23:02.508Z"},"containers":{"cna":{"title":"Autobahn Python permessage-deflate bypasses maxMessagePayloadSize after inflation","descriptions":[{"lang":"en","value":"Autobahn Python is a WebSocket and WAMP implementation for Python that supports Twisted and asyncio. Prior to 26.7.1, WebSocket endpoints that accept permessage-deflate and rely on maxMessagePayloadSize enforce that limit against the compressed frame length before inflation but do not recheck the decompressed message size before delivery. A remote unauthenticated client can send a valid compressed frame below the configured wire-size limit that expands beyond the application message limit, causing oversized data to be allocated, joined, validated, and passed to application callbacks. This can create resource-exhaustion pressure, but the advisory does not establish confidentiality or integrity impact. This issue is fixed in version 26.7.1."}],"affected":[{"vendor":"crossbario","product":"autobahn-python","versions":[{"version":"< 26.7.1","status":"affected"}]}],"references":[{"url":"https://github.com/crossbario/autobahn-python/security/advisories/GHSA-hxp9-w8x3-p566","name":"https://github.com/crossbario/autobahn-python/security/advisories/GHSA-hxp9-w8x3-p566","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/crossbario/autobahn-python/pull/1916","name":"https://github.com/crossbario/autobahn-python/pull/1916","tags":["x_refsource_MISC"]},{"url":"https://github.com/crossbario/autobahn-python/commit/77d323a30b09b1828ad8be2ce6344e056970e613","name":"https://github.com/crossbario/autobahn-python/commit/77d323a30b09b1828ad8be2ce6344e056970e613","tags":["x_refsource_MISC"]},{"url":"https://github.com/crossbario/autobahn-python/releases/tag/v26_7_1","name":"https://github.com/crossbario/autobahn-python/releases/tag/v26_7_1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-409","lang":"en","description":"CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-770","lang":"en","description":"CWE-770: Allocation of Resources Without Limits or Throttling","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-18T19:42:18.767Z"},"source":{"advisory":"GHSA-hxp9-w8x3-p566","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-77528","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-09-19T13:37:22.821549Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-19T14:11:38.071Z"}}]}}}