CVE-2026-29035
mediumpriority · track · 0EPSS 0.006 · 49 %ileEUEPSS · scored 2026-10-26
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.8–8.3
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (1)
Products and version ranges known to be affected.
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (6)
External citations — patches, advisories, analysis.
- https://github.com/civetweb/civetwebcnnvd
- https://www.vulncheck.com/advisories/civetweb-heap-stack-buffer-overflow-via-websocket-permessage-deflate-decompressioncnnvd
- https://github.com/civetweb/civetwebenisa_euvd
- https://www.vulncheck.com/advisories/civetweb-heap-stack-buffer-overflow-via-websocket-permessage-deflate-decompressionenisa_euvd
- https://github.com/civetweb/civetwebnvd
- https://www.vulncheck.com/advisories/civetweb-heap-stack-buffer-overflow-via-websocket-permessage-deflate-decompressionnvd
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