CivetWeb (commit 4a4f0c95) contains a heap and stack buffer overflow vulnerability in the read_websocket() function that allows unauthenticated… (CVE-2026-29035)
CivetWeb contains a heap and stack buffer overflow vulnerability in the read_websocket() function that can be triggered by unauthenticated remote attackers. This occurs when both USE_ZLIB and MG_EXPERIMENTAL_INTERFACES are defined, allowing crafted compressed WebSocket frames with the RSV1 bit set to cause out-of-bounds writes. The vulnerability can lead to heap metadata corruption, denial of service, or potential code execution.
AI Analysis
Technical Summary
CVE-2026-29035 is a heap and stack buffer overflow vulnerability in CivetWeb at commit 4a4f0c95 within the read_websocket() function. When both USE_ZLIB and MG_EXPERIMENTAL_INTERFACES are defined, an attacker can negotiate permessage-deflate during the WebSocket handshake and send a crafted compressed frame with the RSV1 bit set. This causes the server to write a 4-byte zlib sync trailer out-of-bounds past the allocated buffer, corrupting heap metadata. The impact includes denial of service or potential remote code execution. The vulnerability requires no authentication but has a high attack complexity.
Potential Impact
The vulnerability allows unauthenticated remote attackers to corrupt memory by sending specially crafted compressed WebSocket frames. This memory corruption can lead to denial of service or potentially remote code execution on the affected server. The CVSS 3.1 base score is 6.5, indicating a high severity with no confidentiality impact, limited integrity impact, and high availability impact.
Mitigation Recommendations
No patch or official fix information is currently available. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is released, avoid enabling both USE_ZLIB and MG_EXPERIMENTAL_INTERFACES simultaneously or disable permessage-deflate negotiation in WebSocket handshakes if possible to mitigate exposure.
CivetWeb (commit 4a4f0c95) contains a heap and stack buffer overflow vulnerability in the read_websocket() function that allows unauthenticated… (CVE-2026-29035)
Description
CivetWeb contains a heap and stack buffer overflow vulnerability in the read_websocket() function that can be triggered by unauthenticated remote attackers. This occurs when both USE_ZLIB and MG_EXPERIMENTAL_INTERFACES are defined, allowing crafted compressed WebSocket frames with the RSV1 bit set to cause out-of-bounds writes. The vulnerability can lead to heap metadata corruption, denial of service, or potential code execution.
CVSS v3.1
Score 6.5medium
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-29035 is a heap and stack buffer overflow vulnerability in CivetWeb at commit 4a4f0c95 within the read_websocket() function. When both USE_ZLIB and MG_EXPERIMENTAL_INTERFACES are defined, an attacker can negotiate permessage-deflate during the WebSocket handshake and send a crafted compressed frame with the RSV1 bit set. This causes the server to write a 4-byte zlib sync trailer out-of-bounds past the allocated buffer, corrupting heap metadata. The impact includes denial of service or potential remote code execution. The vulnerability requires no authentication but has a high attack complexity.
Potential Impact
The vulnerability allows unauthenticated remote attackers to corrupt memory by sending specially crafted compressed WebSocket frames. This memory corruption can lead to denial of service or potentially remote code execution on the affected server. The CVSS 3.1 base score is 6.5, indicating a high severity with no confidentiality impact, limited integrity impact, and high availability impact.
Mitigation Recommendations
No patch or official fix information is currently available. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is released, avoid enabling both USE_ZLIB and MG_EXPERIMENTAL_INTERFACES simultaneously or disable permessage-deflate negotiation in WebSocket handshakes if possible to mitigate exposure.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-xvrx-cw3m-h23c
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-29035"]
- Ecosystems
- []
- Database Specific Severity
- HIGH
- Cvss Version
- 3.1
Threat ID: 6a7c9b6dbf8831d539cdff13
Added to database: 08/12/2026, 16:12:29 UTC
Last enriched: 08/12/2026, 17:22:45 UTC
Last updated: 08/12/2026, 17:22:45 UTC
Views: 2
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