{"id":"UBUNTU-CVE-2026-29035","details":"CivetWeb (commit 4a4f0c95) contains a heap and stack buffer overflow vulnerability in the read_websocket() function that allows unauthenticated remote attackers to corrupt memory by sending compressed WebSocket frames when both USE_ZLIB and MG_EXPERIMENTAL_INTERFACES are defined. Attackers can negotiate permessage-deflate during the WebSocket handshake and send a crafted frame with the RSV1 bit set, causing the server to write a 4-byte zlib sync trailer out-of-bounds past the allocated buffer, leading to heap metadata corruption, denial of service, or potential code execution.","modified":"2026-09-07T03:45:02.840559262Z","published":"2026-08-11T21:17:00Z","withdrawn":"2026-09-07T01:37:06Z","upstream":["CVE-2026-29035"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-29035"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-29035"},{"type":"REPORT","url":"https://github.com/civetweb/civetweb"},{"type":"REPORT","url":"https://www.vulncheck.com/advisories/civetweb-heap-stack-buffer-overflow-via-websocket-permessage-deflate-decompression"}],"affected":[{"package":{"name":"civetweb","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/civetweb?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.13+dfsg-5","1.15+dfsg-1","1.15+dfsg-3"],"ecosystem_specific":{"binaries":[{"binary_name":"civetweb","binary_version":"1.15+dfsg-3"},{"binary_name":"libcivetweb1","binary_version":"1.15+dfsg-3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-29035.json"}},{"package":{"name":"civetweb","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/civetweb?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.16+dfsg-1","1.16+dfsg-1build1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.16+dfsg-1build1","binary_name":"civetweb"},{"binary_name":"libcivetweb1","binary_version":"1.16+dfsg-1build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-29035.json"}},{"package":{"name":"civetweb","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/civetweb?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.16+dfsg-2","1.16+dfsg-3"],"ecosystem_specific":{"binaries":[{"binary_version":"1.16+dfsg-3","binary_name":"civetweb"},{"binary_name":"libcivetweb1","binary_version":"1.16+dfsg-3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-29035.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}