{"id":"CVE-2026-29035","aliases":["DEBIAN-CVE-2026-29035","EUVD-2026-56944","GHSA-xvrx-cw3m-h23c","UBUNTU-CVE-2026-29035"],"status":"published","title":"CivetWeb Heap/Stack Buffer Overflow via WebSocket permessage-deflate Decompression","description":"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.","severity":{"version":"4.0","score":8.3,"vector":"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","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00612,"percentile":0.49596,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-787"],"published":"2026-08-11T20:14:00Z","modified":"2026-09-25T09:00:08Z","affected":[{"source":"osv","ecosystem":"Debian:12","package":"civetweb","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.15+dfsg-4","1.16+dfsg-1","1.16+dfsg-2","1.16+dfsg-3","1.16+dfsg-4","1.16+dfsg-5","1.16+dfsg-6"]},{"source":"osv","ecosystem":"Debian:13","package":"civetweb","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.16+dfsg-2","1.16+dfsg-2+deb13u1","1.16+dfsg-3","1.16+dfsg-4","1.16+dfsg-5","1.16+dfsg-6"]},{"source":"osv","ecosystem":"Debian:14","package":"civetweb","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.16+dfsg-2","1.16+dfsg-3","1.16+dfsg-4","1.16+dfsg-5","1.16+dfsg-6"]}],"products":[{"vendor":"civetweb","product":"civetweb"}],"references":[{"url":"https://github.com/civetweb/civetweb","tags":["product","report"]},{"url":"https://www.vulncheck.com/advisories/civetweb-heap-stack-buffer-overflow-via-websocket-permessage-deflate-decompression","tags":["third-party-advisory","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-29035"},{"url":"https://github.com/advisories/GHSA-xvrx-cw3m-h23c"},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-29035","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-29035","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-29035","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-29035","title":"CivetWeb Heap/Stack Buffer Overflow via WebSocket permessage-deflate Decompression","description":"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.","status":"published","published":"2026-08-11T20:14:00.402Z","modified":"2026-08-14T16:49:40.759Z","cvss":[{"version":"4.0","score":8.3,"vector":"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","level":"high","assessor":"cna"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-787"],"updated_at":"2026-11-02T14:19:56.284359Z"}],"euvd":[{"id":"EUVD-2026-56944","description":"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.","status":"published","published":"2026-08-11T20:14:00Z","modified":"2026-08-14T16:49:40Z","cvss":[{"version":"4.0","score":8.3,"vector":"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","level":"high"}],"updated_at":"2026-11-02T18:01:54.570698Z"}],"ghsa":[{"id":"GHSA-xvrx-cw3m-h23c","title":"CivetWeb (commit 4a4f0c95) contains a heap and stack buffer overflow vulnerability in the...","description":"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.","status":"published","published":"2026-08-11T21:33:11Z","modified":"2026-08-11T21:33:18Z","cvss":[{"version":"4.0","score":8.3,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H","level":"medium"}],"cwes":["CWE-787"],"updated_at":"2026-11-02T15:10:21.509652Z"}],"nvd":[{"id":"CVE-2026-29035","description":"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.","status":"published","published":"2026-08-11T21:17:35.507Z","modified":"2026-09-24T20:32:04.063Z","cvss":[{"version":"4.0","score":8.3,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H","level":"medium","assessor":"secondary"}],"cwes":["CWE-787"],"updated_at":"2026-11-02T14:12:36.880938Z"}],"osv":[{"id":"DEBIAN-CVE-2026-29035","description":"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.","status":"published","published":"2026-08-11T21:17:35.507Z","modified":"2026-09-25T09:00:08.968960089Z","cvss":[{"version":"4.0","score":8.3,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"}],"updated_at":"2026-11-02T15:45:53.877573Z"},{"id":"UBUNTU-CVE-2026-29035","description":"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.","status":"withdrawn","published":"2026-08-11T21:17:00Z","modified":"2026-09-07T03:45:02.840559262Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H","level":"medium"},{"version":"4.0","score":8.3,"vector":"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","level":"high"}],"updated_at":"2026-11-02T16:56:11.640778Z"}]}}