CVE-2026-29035
Published: August 11th, 2026
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.
MEDIUM
CVSS v3: 6.5
CVSS v3: 6.5
Status
| DocFilters Release | Package | State | Justification | Comment |
|---|---|---|---|---|
| 26.3 | zlib (1.3) | Needs Triage | ||
| 26.2 | zlib (1.3) | Needs Triage | ||
| 26.1 | zlib (1.3) | Needs Triage | ||
| 25.4 | zlib (1.3) | Needs Triage | ||
| 25.3 | zlib (1.3) | Needs Triage | ||
| 25.2 | zlib (1.3) | Needs Triage | ||
| 25.1 | zlib (1.3) | Needs Triage | ||
| 24.4 | zlib (1.3) | Needs Triage | ||
| 24.4.0 | zlib (1.3) | Needs Triage | ||
| 24.3 | zlib (1.3) | Needs Triage | ||
| 24.2 | zlib (1.3) | Needs Triage | ||
| 24.1 | zlib (1.3) | Needs Triage | ||
| 23.3 | zlib (1.3) | Needs Triage | ||
| 23.2 | zlib (1.2.12) | Needs Triage | ||
| 23.1 | zlib (1.2.12) | Needs Triage | ||
| 22.4 | zlib (1.2.12) | Needs Triage | ||
| 22.3 | zlib (1.2.12) | Needs Triage | ||
| 22.2 | zlib (1.2.12) | Needs Triage | ||
| 22.1 | zlib (1.2.11) | Needs Triage | ||
| 21.11 | zlib (1.2.11) | Needs Triage | ||
| 21.8 | zlib (1.2.11) | Needs Triage | ||
| 21.5.0 | zlib (1.2.11) | Needs Triage | ||
| 21.2.0 | zlib (1.2.11) | Needs Triage | ||
| 11.4.19.3667 | zlib (1.2.11) | Needs Triage | ||
| 11.4.18.3599 | zlib (1.2.11) | Needs Triage | ||
| 11.4.16.3445 | zlib (1.2.11) | Needs Triage | ||
| 11.4.15.3368 | zlib (1.2.11) | Needs Triage | ||
| 11.4.14.3263 | zlib (1.2.11) | Needs Triage | ||
| 11.4.13.3179 | zlib (1.2.11) | Needs Triage | ||
| 11.4.12.3054 | zlib (1.2.11) | Needs Triage | ||
| 11.4.11.3040 | zlib (1.2.11) | Needs Triage | ||
| 11.4.11.2990 | zlib (1.2.11) | Needs Triage | ||
| 11.4.10.2934 | zlib (1.2.11) | Needs Triage | ||
| 11.4.9.2878 | zlib (1.2.11) | Needs Triage | ||
| 11.4.8.2822 | zlib (1.2.11) | Needs Triage |
Severity score breakdown
Attack Complexity
HIGH
Attack Vector
NETWORK
Availability Impact
HIGH
Base Score
6.5
Base Severity
MEDIUM
Confidentiality Impact
NONE
Integrity Impact
LOW
Privileges Required
NONE
Scope
UNCHANGED
User Interaction
NONE
Vector String
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Version
3.1