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HAProxy

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medium advisory

HAProxy Denial of Service Vulnerability (CVE-2026-26080)

A denial of service vulnerability (CVE-2026-26080) in HAProxy Community Edition versions 3.2.x through 3.3.x before 3.3.3, HAProxy Enterprise, and ALOHA can lead to a loop or crash due to mishandled varint, impacting service availability.

HAProxy Community Edition +3 denial-of-service vulnerability haproxy load-balancer
1c
high advisory

HAProxy CVE-2021-40346 Integer Overflow Leading to HTTP Request Smuggling and ACL Bypass

A critical integer overflow vulnerability, CVE-2021-40346, in HAProxy's `htx_add_header()` function allows unauthenticated attackers to bypass access control rules by crafting HTTP requests with specific header name lengths, leading to HTTP request smuggling and unauthorized access to backend paths, for which a public exploit is available.

HAProxy +4 integer-overflow http-smuggling acl-bypass webserver
2t 1c
medium advisory

CVE-2026-55204: HAProxy Null Pointer Dereference Leads to Denial of Service

An unauthenticated attacker can exploit CVE-2026-55204, a null pointer dereference vulnerability in HAProxy through version 3.4.0, by triggering excessive HPACK dynamic table insertions under memory pressure, causing HAProxy worker processes to crash and resulting in a denial of service.

HAProxy 3.4.0 denial-of-service vulnerability HAProxy CVE-2026-55204
2r 1t
high advisory

CVE-2026-55203 HAProxy Integer Overflow in FastCGI Handling

An integer overflow vulnerability (CVE-2026-55203) in HAProxy through version 3.4.0 allows malicious FastCGI backends to desynchronize the FCGI framing parser, leading to request routing errors, response smuggling, or memory safety issues.

HAProxy vulnerability fastcgi integer-overflow webserver proxy
2r 3t