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haproxy vulnerabilities

Vulnerabilities published for haproxy in the last 30 days: 1. Listed in the KEV catalogue: 0.

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Vulnerabilities: 38

  1. CVE-2026-110353

    High · CVSS 7.5EPSS 0.68%Fix available

    CVE-2026-110353

    HAProxy 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.

    haproxyOperating systems Web servers
    • Update to 3.2.26-1
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  4. CVE-2026-55204

    High · CVSS 8.7EPSS 0.48%Fix available

    HAProxy - NULL Pointer Dereference in hpack_dht_insert Function

    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_defrag() when the memory pool is exhausted. An attacker can trigger HPACK dynamic table insertions under memory pressure to dereference a NULL pointer and crash HAProxy worker processes, causing denial of service.

    haproxyOperating systems Web servers
    • Update to 3.2.20-1
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗Source advisory 3 ↗

  5. CVE-2026-55203

    Critical · CVSS 9EPSS 0.33%Fix available

    HAProxy - Integer Overflow in FCGI Demux Record Length Field

    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 contentLength is 65535 and paddingLength is 1 or more, the drl field wraps to 0, causing incorrect record consumption and allowing malicious FastCGI backends to desynchronize the FCGI framing parser, potentially causing request routing errors, response smuggling, or memory safety issues.

    haproxyOperating systems Web servers
    • Update to 3.2.20-1
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗Source advisory 3 ↗

  6. CVE-2026-33555

    Medium · CVSS 4EPSS 0.6%Fix available

    CVE-2026-33555

    An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.

    haproxyOperating systems Web servers
    • Update to 3.2.15-1
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗Source advisory 3 ↗

  9. CVE-2024-53008

    Medium · CVSS 5.3EPSS 1.02%Fix available

    CVE-2024-53008

    Inconsistent interpretation of HTTP requests ('HTTP Request/Response Smuggling') issue exists in HAProxy. If this vulnerability is exploited, a remote attacker may access a path that is restricted by ACL (Access Control List) set on the product. As a result, the attacker may obtain sensitive information.

    haproxyOperating systems Web servers
    • Update to 2.9.10-1
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗Source advisory 3 ↗

  14. CVE-2023-40225

    High · CVSS 7.2EPSS 2.15%Fix available

    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 headers, violating RFC 9110 section 8.6. In uncommon cases, an HTTP/1 server behind HAProxy may interpret the payload as an extra request.

    haproxyOperating systems Web servers
    • Update to 2.6.15-1
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗Source advisory 3 ↗

  16. CVE-2023-0836

    High · CVSS 7.5EPSS 1.2%Fix available

    CVE-2023-0836

    An information leak vulnerability was discovered in HAProxy 2.1, 2.2 before 2.2.27, 2.3, 2.4 before 2.4.21, 2.5 before 2.5.11, 2.6 before 2.6.8, 2.7 before 2.7.1. There are 5 bytes left uninitialized in the connection buffer when encoding the FCGI_BEGIN_REQUEST record. Sensitive data may be disclosed to configured FastCGI backends in an unexpected way.

    haproxyOperating systems Web servers
    • Update to 2.6.8-1
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗Source advisory 3 ↗

  17. CVE-2023-0056

    Medium · CVSS 6.5EPSS 1.83%Fix available

    CVE-2023-0056

    An uncontrolled resource consumption vulnerability was discovered in HAProxy which could crash the service. This issue could allow an authenticated remote attacker to run a specially crafted malicious server in an OpenShift cluster. The biggest impact is to availability.

    haproxyOperating systems Web servers
    • Update to 2.6.8-1
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  18. CVE-2023-25725

    Critical · CVSS 9.1EPSS 5.45%Fix available

    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 empty header field names, which could be used to truncate the list of HTTP headers and thus make some headers disappear after being parsed and processed for HTTP/1.0 and HTTP/1.1. For HTTP/2 and HTTP/3, the impact is limited because the headers disappear before being parsed and processed, as if they had not been sent by the client. The fixed versions are 2.7.3, 2.6.9, 2.5.12, 2.4.22, 2.2.29, and 2.0.31.

    haproxyOperating systems Web servers
    • Update to 2.6.8-2
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗Source advisory 3 ↗

  19. CVE-2022-0711

    High · CVSS 7.5EPSS 16.56%Fix available

    CVE-2022-0711

    A flaw was found in the way HAProxy processed HTTP responses containing the "Set-Cookie2" header. This flaw could allow an attacker to send crafted HTTP response packets which lead to an infinite loop, eventually resulting in a denial of service condition. The highest threat from this vulnerability is availability.

    haproxyOperating systems Web servers
    • Update to 2.4.13-1
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗Source advisory 3 ↗

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