HAProxy 1.2.18 → 3.1.17

Vulnerabilities fixed by this upgrade

• 7.5 CVE-2026-55203 HAProxy through 3.4.0, fixed in commit 5985276, contains an integer overflow vulnerability in the fcgi_conn structure's drl field that allows buffer misparse as new FCGI record headers. When conten…
• 7.5 CVE-2026-55204 HAProxy through 3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpack_dht_insert() within src/hpack-tbl.c that fails to validate the return value of hpack_dht_…
• 8.2 CVE-2023-45539 HAProxy before 2.8.2 accepts # as part of the URI component, which might allow remote attackers to obtain sensitive information or have unspecified other impact upon misinterpretation of a path_end…
• 7.2 CVE-2023-40225 HAProxy through 2.0.32, 2.1.x and 2.2.x through 2.2.30, 2.3.x and 2.4.x through 2.4.23, 2.5.x and 2.6.x before 2.6.15, 2.7.x before 2.7.10, and 2.8.x before 2.8.2 forwards empty Content-Length head…
• 9.1 CVE-2023-25725 HAProxy before 2.7.3 may allow a bypass of access control because HTTP/1 headers are inadvertently lost in some situations, aka "request smuggling." The HTTP header parsers in HAProxy may accept em…
• 9.8 CVE-2019-19330 The HTTP/2 implementation in HAProxy before 2.0.10 mishandles headers, as demonstrated by carriage return (CR, ASCII 0xd), line feed (LF, ASCII 0xa), and the zero character (NUL, ASCII 0x0), aka In…
• 7.5 CVE-2019-18277 A flaw was found in HAProxy before 2.0.6. In legacy mode, messages featuring a transfer-encoding header missing the "chunked" value were not being correctly rejected. The impact was limited but if…
• 7.5 CVE-2018-20102 An out-of-bounds read in dns_validate_dns_response in dns.c was discovered in HAProxy through 1.8.14. Due to a missing check when validating DNS responses, remote attackers might be able read the 1…
• 7.5 CVE-2018-20103 An issue was discovered in dns.c in HAProxy through 1.8.14. In the case of a compressed pointer, a crafted packet can trigger infinite recursion by making the pointer point to itself, or create a l…
• 7.5 CVE-2018-14645 A flaw was discovered in the HPACK decoder of HAProxy, before 1.8.14, that is used for HTTP/2. An out-of-bounds read access in hpack_valid_idx() resulted in a remote crash and denial of service.
• 7.5 CVE-2018-10184 An issue was discovered in HAProxy before 1.8.8. The incoming H2 frame length was checked against the max_frame_size setting instead of being checked against the bufsize. The max_frame_size only ap…
• 5.1 CVE-2012-2942 Buffer overflow in the trash buffer in the header capture functionality in HAProxy before 1.4.21, when global.tune.bufsize is set to a value greater than the default and header rewriting is enabled…

Breaking changes

None in the release notes.

Security changes

• security Fixes CVE-2026-55203: HAProxy through 3.4.0, fixed in commit 5985276, contains an integer overflow vulnerability in the fcgi_conn structure's drl field that allows buffer misparse as new FCGI record headers. When conten… in 2.4.36
• security Fixes CVE-2026-55204: HAProxy through 3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpack_dht_insert() within src/hpack-tbl.c that fails to validate the return value of hpack_dht_… in 2.4.36

Every release in between