Haproxy vulnerabilities

41 vulnerabilities

Known vulnerabilities in Haproxy products, newest first, with CVSS severity, EPSS, KEV listings and ransomware use, across 11 products.

Products

11
7.5CVE-2026-110354haproxy technologieshaproxy kubernetes ingress controller+3HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via an HTTP/1.1 chunked request. Although the H1 multiplexer drains the request before closing the stream, the parser repeatedly re-processes the same bytes without making progress. The affected thread stays busy at 100% CPU after timeouts expire and after the client disconnects, and repeated requests can consume all worker threads until the process is restarted.7.5CVE-2026-110353haproxyhaproxy+3HAProxy 3.2 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (worker-thread CPU exhaustion) via a truncated HTTP/2 PING frame. h2c_handle_ping in src/mux_h2.c does not check for a short read, unlike the other H2 frame handlers. Because the incomplete frame cannot be processed, its data is never consumed, and the H2 multiplexer tasklet is repeatedly woken by that pending data without making progress. The CPU spins until timeout http-request closes the connection, and an attacker opening many such connections can sustain high CPU usage.9.8CVE-2026-109575haproxydata plane api ce+1
EPSS score
0.36%
In HAProxy Data Plane API 2.2.0 through 3.4.3 (and corresponding Enterprise Edition releases), Server.ConfigureAPI() has process-global authentication logic that improperly drops security controls across multiple transport types. When a TLS Certificate Authority (tls_ca) is configured and a numeric TLS port (tls_port) is specified, the application globally disables Basic authentication on its shared internal request handler. Because this handler is shared concurrently among HTTP, HTTPS, and UNIX domain socket listeners, and mutual TLS (mTLS) client certificate verification (tls.RequireAndVerifyClientCert) is enforced exclusively on the HTTPS server path, all other simultaneously active non-mTLS listeners fail open. Consequently, an unauthenticated attacker capable of reaching an affected HTTP or UNIX management endpoint can completely bypass credentials to gain full API administrative access. This allows unauthorized remote or local actors to read sensitive, cleartext HAProxy configuration data or replace the managed configuration entirely via the raw configuration endpoint. This has been fixed in versions 3.4.4, 3.3.9, 3.2.17, 3.0.25, 2.9.29, and their respective EE backports by migrating to a per-request TLS connection-state validation model.5.9CVE-2018-11469canonicalubuntu_linux+3
EPSS score
2.92%
Incorrect caching of responses to requests including an Authorization header in HAProxy 1.8.0 through 1.8.9 (if cache enabled) allows attackers to achieve information disclosure via an unauthenticated remote request, related to the proto_http.c check_request_for_cacheability function.7.5CVE-2018-20103canonicalubuntu_linux+4
EPSS score
6.59%
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 long chain of valid pointers resulting in stack exhaustion.7.5CVE-2018-20615canonicalubuntu_linux+13
EPSS score
4.46%
An out-of-bounds read issue was discovered in the HTTP/2 protocol decoder in HAProxy 1.8.x and 1.9.x through 1.9.0 which can result in a crash. The processing of the PRIORITY flag in a HEADERS frame requires 5 extra bytes, and while these bytes are skipped, the total frame length was not re-checked to make sure they were present in the frame.7.5CVE-2018-20102canonicalubuntu_linux+4
EPSS score
4.15%
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 16 bytes corresponding to an AAAA record from the non-initialized part of the buffer, possibly accessing anything that was left on the stack, or even past the end of the 8193-byte buffer, depending on the value of accepted_payload_size.7.5CVE-2018-14645canonicalubuntu_linux+38
EPSS score
3.07%
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.7.5CVE-2018-10184debianhaproxy+9
EPSS score
8.15%
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 applies to outgoing traffic and not to incoming, so if a large enough frame size is advertised in the SETTINGS frame, a wrapped frame will be defragmented into a temporary allocated buffer where the second fragment may overflow the heap by up to 16 kB. It is very unlikely that this can be exploited for code execution given that buffers are very short lived and their addresses not realistically predictable in production, but the likelihood of an immediate crash is absolutely certain.5CVE-2013-2175canonicalubuntu_linux+6
EPSS score
3.59%
HAProxy 1.4 before 1.4.24 and 1.5 before 1.5-dev19, when configured to use hdr_ip or other "hdr_*" functions with a negative occurrence count, allows remote attackers to cause a denial of service (negative array index usage and crash) via an HTTP header with a certain number of values, related to the MAX_HDR_HISTORY variable.5.1CVE-2013-1912debianhaproxy+3
EPSS score
5.57%
Buffer overflow in HAProxy 1.4 through 1.4.22 and 1.5-dev through 1.5-dev17, when HTTP keep-alive is enabled, using HTTP keywords in TCP inspection rules, and running with rewrite rules that appends to requests, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via crafted pipelined HTTP requests that prevent request realignment from occurring.7.5CVE-2021-40346debianhaproxy+10
EPSS score
58.83%
An integer overflow exists in HAProxy 2.0 through 2.5 in htx_add_header that can be exploited to perform an HTTP request smuggling attack, allowing an attacker to bypass all configured http-request HAProxy ACLs and possibly other ACLs.5.3CVE-2021-39241debianhaproxy+4
EPSS score
1.69%
An issue was discovered in HAProxy 2.0 before 2.0.24, 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. An HTTP method name may contain a space followed by the name of a protected resource. It is possible that a server would interpret this as a request for that protected resource, such as in the "GET /admin? HTTP/1.1 /static/images HTTP/1.1" example.7.5CVE-2021-39240debianhaproxy+3
EPSS score
2.21%
An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It does not ensure that the scheme and path portions of a URI have the expected characters. For example, the authority field (as observed on a target HTTP/2 server) might differ from what the routing rules were intended to achieve.7.5CVE-2021-39242debianhaproxy+3
EPSS score
2.23%
An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It can lead to a situation with an attacker-controlled HTTP Host header, because a mismatch between Host and authority is mishandled.5CVE-2015-3281canonicalubuntu_linux+34
EPSS score
4.33%
The buffer_slow_realign function in HAProxy 1.5.x before 1.5.14 and 1.6-dev does not properly realign a buffer that is used for pending outgoing data, which allows remote attackers to obtain sensitive information (uninitialized memory contents of previous requests) via a crafted request.5.3CVE-2016-2102chainguardhaproxy-2.4+9
EPSS score
2.29%
HAProxy statistics in openstack-tripleo-image-elements are non-authenticated over the network.7.5CVE-2016-5360canonicalubuntu_linux+3
EPSS score
42.82%
HAproxy 1.6.x before 1.6.6, when a deny comes from a reqdeny rule, allows remote attackers to cause a denial of service (uninitialized memory access and crash) or possibly have unspecified other impact via unknown vectors.6.4CVE-2025-59303haproxyhaproxy kubernetes ingress controller
EPSS score
0.26%
HAProxy Kubernetes Ingress Controller before 3.1.13, when the config-snippets feature flag is used, accepts config snippets from users with create/update permissions. This can result in obtaining an ingress token secret as a response. The fixed versions of HAProxy Enterprise Kubernetes Ingress Controller are 3.0.16-ee1, 1.11.13-ee1, and 1.9.15-ee1.7.5CVE-2025-11230chainguardhaproxy-2.4+28
EPSS score
0.74%
Inefficient algorithm complexity in mjson in HAProxy allows remote attackers to cause a denial of service via specially crafted JSON requests.