CVE-2026-29035 (GCVE-0-2026-29035)
Vulnerability from cvelistv5 – Published: 2026-08-11 20:14 – Updated: 2026-08-14 16:49
VLAI
EPSS
VEX
Title
CivetWeb Heap/Stack Buffer Overflow via WebSocket permessage-deflate Decompression
Summary
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
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-12 16:03 UTC
CWE
- CWE-787 - Out-of-bounds Write
Assigner
VulnCheck
CNA
References
2 references
| URL | Tags |
|---|---|
| https://github.com/civetweb/civetweb | product |
| https://www.vulncheck.com/advisories/civetweb-hea… | third-party-advisory |
Impacted products
Date Public
2026-08-11 00:00
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