{"id":"CVE-2026-66338","title":"Libsoup: libsoup: http request smuggling via permissive chunk-size parsing in soup_body_input_stream_read_chunked()","summary":"A flaw was found in libsoup. The chunked transfer encoding parser uses a permissive parsing function for chunk sizes that silently accepts inputs violating RFC 9112, including leading whitespace, plus sign prefixes, and trailing invalid …","severity":"medium","cvss":5.4,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N","cvssSource":"cna","cwe":["CWE-444"],"vendor":"Red Hat","product":"libsoup3","affected":["libsoup3 (all versions)","libsoup (all versions)","libsoup (all versions)","libsoup (all versions)","libsoup (all versions)"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-07-27T14:34:59.011664Z"},"published":"2026-07-24","updated":"2026-11-06","sourceUpdated":"2026-11-06T19:27:20.998Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-66338","references":[{"url":"https://access.redhat.com/security/cve/CVE-2026-66338"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2506950","label":"RHBZ#2506950"}],"tags":["cve.org"],"epss":0.00291,"epssPercentile":0.21793,"ingestedAt":"2026-11-06T20:03:04.275Z","slug":"CVE-2026-66338","body":"## Overview\n\nA flaw was found in libsoup. The chunked transfer encoding parser uses a permissive parsing function for chunk sizes that silently accepts inputs violating RFC 9112, including leading whitespace, plus sign prefixes, and trailing invalid characters. When libsoup operates behind a strict frontend proxy, this parsing differential can be exploited to smuggle HTTP requests.\n\n## Affected\n\n- `libsoup3 (all versions)`\n- `libsoup (all versions)`\n- `libsoup (all versions)`\n- `libsoup (all versions)`\n- `libsoup (all versions)`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":29.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}