{"cve":"CVE-2026-77528","nvd":{"published":"2026-09-18T20:17:22.830","modified":"2026-09-24T21:25:27.050","status":"Deferred","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3},"cwes":["CWE-409","CWE-770"],"references":["https://github.com/crossbario/autobahn-python/commit/77d323a30b09b1828ad8be2ce6344e056970e613","https://github.com/crossbario/autobahn-python/pull/1916","https://github.com/crossbario/autobahn-python/releases/tag/v26_7_1","https://github.com/crossbario/autobahn-python/security/advisories/GHSA-hxp9-w8x3-p566"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:55:23.253742848+00:00"},"epss":{"cve":"CVE-2026-77528","score":0.00524,"percentile":0.44447,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-hxp9-w8x3-p566","url":"https://osv.dev/vulnerability/GHSA-hxp9-w8x3-p566","summary":"Autobahn Python permessage-deflate bypasses maxMessagePayloadSize after inflation","modified":"2026-10-01T17:55:38.804385392Z","packages":[{"ecosystem":"PyPI","name":"autobahn","purl":"pkg:pypi/autobahn","ranges":["<26.7.1"],"fixed":["26.7.1"]},{"ecosystem":"PyPI","name":"crossbar","purl":"pkg:pypi/crossbar","ranges":["<26.7.1"],"fixed":["26.7.1"]}]},{"id":"PYSEC-2026-4027","url":"https://osv.dev/vulnerability/PYSEC-2026-4027","summary":"Autobahn Python permessage-deflate bypasses maxMessagePayloadSize after inflation","modified":"2026-10-01T17:55:38.804385392Z","packages":[{"ecosystem":"PyPI","name":"autobahn","purl":"pkg:pypi/autobahn","ranges":["<26.7.1"],"fixed":["26.7.1"]}]},{"id":"PYSEC-2026-4031","url":"https://osv.dev/vulnerability/PYSEC-2026-4031","summary":"Autobahn Python permessage-deflate bypasses maxMessagePayloadSize after inflation","modified":"2026-10-01T17:55:38.804385392Z","packages":[{"ecosystem":"PyPI","name":"crossbar","purl":"pkg:pypi/crossbar","ranges":["<26.7.1"],"fixed":["26.7.1"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}