Web servers stack vulnerabilities · Page 4

Traefik before v2.11.52 Authentication Bypass via ReplacePathRegex

Traefik versions <= v2.11.51, >= v3.6.0 <= v3.6.22, and >= v3.7.0 <= v3.7.6 contain an authentication bypass via path traversal in the ReplacePathRegex middleware. When ReplacePathRegex is configured with a regex that captures user-controlled path segments without a mandatory path separator (e.g. regex "^/api(.*)", replacement "/$1"), the middleware forwards the replaced path to the backend without validating that it matches its normalized form. An unauthenticated remote attacker can send a crafted request (e.g. GET /api../admin) that produces an un-normalized path such as /../admin, which a backend that normalizes paths resolves to a protect

• Update to 2.11.52
• Update to 3.6.23
• Update to 3.7.7

CVE-2026-26081

HAProxy Community Edition 3.0 through 3.3 before 3.3.3 lacks a length check for the NEW_TOKEN format. HAProxy Enterprise and ALOHA are also affected.

• Update to 3.0.11-1+deb13u2
• Update to 3.0.12
• Update to 3.0.12-0ubuntu0.25.10.3
• Update to 3.1.14
• Update to 3.2.11-2
• Update to 3.2.12
• Update to 3.3.3

CVE-2026-26080

HAProxy Community Edition 3.2.x through 3.3.x before 3.3.3 can enter a loop or crash because varint is mishandled. HAProxy Enterprise and ALOHA are also affected.

• Update to 3.2.11-2
• Update to 3.2.12
• Update to 3.3.3

NGINX ngx_http_slice_module vulnerability

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_slice_module module. When the slice directive and unnamed regex captures are configured or when a background cache update happens, unauthenticated attackers can send requests that may cause uninitialized memory access in the NGINX worker process, leading to limited disclosure of memory or a restart. Impact: This vulnerability may allow remote, unauthenticated attackers to have limited control to disclose memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only. Note: The ngx_http_slice_module module is not ena

• Update to 1.18.0-6ubuntu14.17
• Update to 1.22.1-9+deb12u10
• Update to 1.24.0-2ubuntu7.14
• Update to 1.26.3-3+deb13u8
• Update to 1.28.3-2ubuntu1.7
• Update to 1.30.1-7
• Update to 1.30.4
• Update to 1.31.3
• Update to 37.0.3.1

NGINX ngx_http_ssi_module vulnerability

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a use-after-free in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process. Impact: This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker

• Update to 1.18.0-6ubuntu14.17
• Update to 1.22.1-9+deb12u10
• Update to 1.24.0-2ubuntu7.14
• Update to 1.26.3-3+deb13u8
• Update to 1.28.3-2ubuntu1.7
• Update to 1.30.1-7
• Update to 1.30.4
• Update to 1.31.3
• Update to 37.0.3.1

NGINX Map directive and Regex matching vulnerability

A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a string expression references the map's regex capture variables before referencing the map output variable. Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Ran

• Update to 1.18.0-6ubuntu14.21
• Update to 1.22.1-9+deb12u10
• Update to 1.24.0-2ubuntu7.18
• Update to 1.26.3-3+deb13u8
• Update to 1.28.3-2ubuntu1.11
• Update to 1.30.4
• Update to 1.30.4-3
• Update to 1.31.3
• Update to 37.0.3.1

Traefik: headerField underscore-variant identity spoofing in BasicAuth / DigestAuth / ForwardAuth

Traefik is an HTTP reverse proxy and load balancer. Prior to v2.11.51, v3.6.22, and v3.7.6, Traefik's BasicAuth, DigestAuth, and ForwardAuth middlewares strip canonical-cased spoofed identity headers before writing Traefik's own value, but do not account for underscore-variant header names, which many backends normalize identically to dashed forms. An attacker able to reach a protected route can inject an underscore-variant header that survives Traefik's stripping and reaches the backend alongside, or on the unauthenticated ForwardAuth authResponseHeaders path instead of, the value Traefik intended to set, spoofing identity or authorization c

Traefik: Gateway HTTPRoute backendRef filters can leak backend context across routes sharing a Service:port

Traefik is an open source HTTP reverse proxy and load balancer. From v3.7.0 prior to v3.7.6, Traefik's Kubernetes Gateway API provider may resolve two accepted HTTPRoutes that target the same backend Service:port but configure different backendRef filters to the same child service and apply only one route's filter set to all requests reaching that backend. In Gateway deployments where backendRef filters set security-sensitive headers, such as tenant identity, authorization context, or values the backend trusts, an attacker who can create an accepted HTTPRoute sharing the same backend Service:port may cause their route's filter context to be a

ForwardAuth middleware leaks X-Forwarded-Port spoofing via untrusted X-Forwarded-Proto when trustForwardHeader=false

Traefik is an HTTP reverse proxy and load balancer. Prior to v2.11.51, v3.6.22, and v3.7.6, Traefik's ForwardAuth middleware, even when configured with trustForwardHeader: false, derives the X-Forwarded-Port header sent to the authentication service from the original incoming request instead of the sanitized forwarded request. As a result, an unauthenticated remote attacker can inject an X-Forwarded-Proto: https header over a plain HTTP connection and cause Traefik to forward X-Forwarded-Port: 443 to the authentication service, bypassing port-based authorization checks. This issue is fixed in versions v2.11.51, v3.6.22, and v3.7.6.

Traefik Kubernetes Ingress NGINX provider fails open when auth-secret resolution fails

Traefik is an HTTP reverse proxy and load balancer. From 3.7.0-ea.1 until 3.7.5, there is a medium severity vulnerability in Traefik's Kubernetes Ingress NGINX provider that causes affected routes to fail open. When an Ingress explicitly enables BasicAuth or DigestAuth through the supported nginx.ingress.kubernetes.io/auth-type and auth-secret annotations, but the referenced auth Secret cannot be resolved or parsed, Traefik logs the resolution error, skips installing the authentication middleware, and still emits a router to the backend service. A route that operators intended to protect is therefore published to the data plane without its au

Traefik: Kubernetes Gateway crossProviderNamespaces bypass allows HTTPRoute outside the allowlist to expose internal Traefik services

Traefik is an HTTP reverse proxy and load balancer. Prior to 3.6.21 and 3.7.5, there is a high severity vulnerability in Traefik's Kubernetes Gateway provider affecting the crossProviderNamespaces allowlist. For HTTPRoute rules that declare multiple (WRR) backendRefs, Traefik evaluates the allowlist against the target backendRef.namespace instead of the route's own namespace. As a result, an HTTPRoute created in a namespace that is not allow-listed can reference a cross-provider TraefikService such as api@internal, dashboard@internal or rest@internal by pointing backendRef.namespace at an allow-listed namespace covered by a Gateway API Refere

Traefik: HTTP/3 mTLS bypass via exact SNI TLSOptions lookup for wildcard and mixed-case hosts

Traefik is an HTTP reverse proxy and load balancer. Versions prior to 3.7.3, 3.6.18, and 2.11.51 have a critical vulnerability in Traefik's HTTP/3 (QUIC) TLS configuration selection that allows unauthenticated clients to bypass router-specific mTLS enforcement. When HTTP/3 is enabled on an entrypoint, the TLS handshake selects the applicable TLS configuration through an exact, case-sensitive lookup on the SNI value, which fails to match wildcard host patterns (e.g., *.example.com) or case variants of the configured hostname. Because the handshake falls back to the default TLS configuration — which may not require client certificates — a clien

Traefik: SNICheck ignores wildcard TLSOptions mappings, allowing domain-fronted mTLS bypass

Traefik is an HTTP reverse proxy and load balancer. From 3.7.0 until 3.7.3, there is a high severity vulnerability in Traefik's domain-fronting protection (SNICheck) that allows an unauthenticated client to bypass mutual TLS enforced through wildcard router TLSOptions. When a router uses a wildcard host rule such as Host(*.example.com) with stricter TLS options (for example RequireAndVerifyClientCert), SNICheck resolves the TLS options for the HTTP Host header using exact map lookups only and never applies wildcard matching. If another permissive SNI is served on the same entrypoint, an attacker can complete the TLS handshake under the permis

Traefik StripPrefix Route-Level Auth Bypass via Path Normalization

Traefik is an HTTP reverse proxy and load balancer. Prior to 2.11.48, 3.6.19, and 3.7.3, there is a high severity vulnerability in Traefik's StripPrefix middleware that allows an unauthenticated attacker to bypass route-level authentication and authorization. When a public router matches on a PathPrefix rule and applies the StripPrefix middleware, a request path containing .. or its percent-encoded form %2e%2e can match the public route at routing time and then, after the prefix is stripped and the path is normalized, resolve to a path served by a separate, authenticated router. As a result, an attacker can reach protected backend paths — suc

Traefik - Denial of Service via HTTP/2 Request Handling

Traefik before 2.10.5 and 3.0.0-beta4 is affected by a denial-of-service vulnerability in HTTP/2 request handling inherited from the Go standard library's HTTP/2 implementation (CVE-2023-44487 / CVE-2023-39325, the 'Rapid Reset' technique). A remote attacker can rapidly create and cancel HTTP/2 streams to exhaust server resources and cause service unavailability.

• Update to 2.10.5
• Update to 3.0.0-beta4

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.

• Update to 2.4.30-0ubuntu0.22.04.2
• Update to 2.8.16-0ubuntu0.24.04.3
• Update to 3.0.12-0ubuntu0.25.10.5
• Update to 3.2.20-1
• Update to 3.2.9-1ubuntu2.2

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.

• Update to 2.4.30-0ubuntu0.22.04.2
• Update to 2.8.16-0ubuntu0.24.04.3
• Update to 3.0.12-0ubuntu0.25.10.5
• Update to 3.2.20-1
• Update to 3.2.9-1ubuntu2.2

NGINX ngx_http_charset_module vulnerability

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module. When content is served or proxied through a location block with both source_charset utf-8; and a charset directive (for example, charset koi8-r;) configured, remote, unauthenticated attackers can send requests (in conjunction with conditions beyond their control) to cause a heap buffer over-read in the NGINX worker process, leading to limited disclosure of memory or a restart. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

• Update to 1.18.0-6ubuntu14.16
• Update to 1.22.1-9+deb12u9
• Update to 1.24.0-2ubuntu7.13
• Update to 1.26.3-3+deb13u7
• Update to 1.28.0-6ubuntu1.8
• Update to 1.28.3-2ubuntu1.6
• Update to 1.30.1-5
• Update to 1.31.2
• Update to 37.0.2.1

NGINX ngx_http_proxy_v2_module and ngx_http_grpc_module vulnerability

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_proxy_v2_module and ngx_http_grpc_module modules. This vulnerability exists when the proxy_http_version to 2 or grpc_pass directives are used to proxy HTTP/2 traffic, the ignore_invalid_headers directive is set to off, and the large_client_header_buffers directive size is larger than 2 megabytes. A remote, unauthenticated attacker, along with conditions beyond their control, could send large headers while creating an upstream request. This may cause a heap-based buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on sys

• Update to 1.18.0-6ubuntu14.16
• Update to 1.22.1-9+deb12u9
• Update to 1.24.0-2ubuntu7.13
• Update to 1.26.3-3+deb13u7
• Update to 1.28.0-6ubuntu1.8
• Update to 1.28.3-2ubuntu1.6
• Update to 1.30.1-5
• Update to 1.31.2
• Update to 37.0.2.1

NGINX Open-Source ngx_http_v3_module vulnerability

NGINX Open Source has a vulnerability in the ngx_http_v3_module module. When NGINX Open Source is configured to use the HTTP/3 QUIC module, a remote unauthenticated attacker along with conditions beyond their control can use a specially crafted HTTP/3 session to reopen a QPACK encoder stream. This may cause a Use-after-Free in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

• Update to 1.31.2