GO-2026-5360 Mattermost allows attackers to take over arbitrary user accounts via overly permissive substring matching flaw in github.com/mattermost/mattermost-server

Mattermost allows attackers to take over arbitrary user accounts via overly permissive substring matching flaw in github.com/mattermost/mattermost-server...

CVE-2026-55602: Improper Input Validation

http-proxy-middleware is node.js http-proxy middleware. From 0.16.0 until 2.0.10, 3.0.6, and 4.1.0, http-proxy-middleware documents router proxy-table entries as host, path, or host+path selectors, but the host+path implementation uses unanchored substring matching on attacker-controlled request...

NPM: undici vulnerable to Set-Cookie SameSite attribute downgrade via permissive substring matching

NPM: undici vulnerable to Set-Cookie SameSite attribute downgrade via permissive substring matching vulnerability discovered by ? in WordPress Npm undici versions 6.27.0...

http-proxy-middleware `router` host+path substring matching allows Host-header-driven backend routing bypass

Summary http-proxy-middleware documents router proxy-table entries as host, path, or host+path selectors, but the host+path implementation uses unanchored substring matching on attacker-controlled request metadata. As a result, a crafted Host header that is only a superstring match for a configur...

GHSA-64MM-VXMG-Q3VJ http-proxy-middleware `router` host+path substring matching allows Host-header-driven backend routing bypass

Summary http-proxy-middleware documents router proxy-table entries as host, path, or host+path selectors, but the host+path implementation uses unanchored substring matching on attacker-controlled request metadata. As a result, a crafted Host header that is only a superstring match for a configur...

PT-2026-50734

Name of the Vulnerable Software and Affected Versions http-proxy-middleware versions 0.16.0 through 2.0.9 http-proxy-middleware versions 3.0.0 through 3.0.5 http-proxy-middleware versions 4.0.0 through 4.0.9 Description An issue exists in the router proxy-table implementation where host+path...

CVE-2026-11525

The issue affects undici’s cookie parsing in Set-Cookie headers. The root cause is a permissive substring match for the SameSite attribute during parsing, accepting any value containing Strict, Lax, or None instead of enforcing a case-insensitive exact match per RFC 6265. This can cause downstrea...

CVE-2026-11525 undici vulnerable to Set-Cookie SameSite attribute downgrade via permissive substring matching

Impact: When undici parses a Set-Cookie header, it accepts any SameSite attribute value that contains Strict, Lax, or None as a substring, rather than the case-insensitive exact match specified by RFC 6265. Non-spec values are silently mapped to one of the three standard tokens. For example,...

CVE-2026-46391

HAX CMS helps manage microsite universe with PHP or NodeJs backends. Starting in version 9.0.1 and prior to version 26.0.0 of @haxtheweb/open-apis, multiple functions conduct substring-only matching to validate hostnames to which basic authorization should be sent. An attacker can append the...

EUVD-2026-34882

HAX CMS helps manage microsite universe with PHP or NodeJs backends. Starting in version 9.0.1 and prior to version 26.0.0 of @haxtheweb/open-apis, multiple functions conduct substring-only matching to validate hostnames to which basic authorization should be sent. An attacker can append the...

PT-2026-41974

Name of the Vulnerable Software and Affected Versions @haxtheweb/open-apis versions 9.0.1 through 25.x Description Multiple functions perform substring-only matching to validate hostnames for basic authorization. This allows an attacker to append matched substrings to an attacker-controlled...

@cyclonedx/cdxgen: Docker registry auth substring match forwards credentials to a different registry

Docker registry auth substring match forwards credentials to a different registry Repository cdxgen/cdxgen Affected product/package - Ecosystem: npm - Package: @cyclonedx/cdxgen - Reviewed tree version: 12.3.3 - Reviewed commit: b1e179869fd7c6032c3d483c3f7bd4d7154ec22b - Affected file:...

EUVD-2026-24151

Tekton Pipelines has VerificationPolicy regex pattern bypass via substring matching...

CVE-2026-25542 Tekton Pipelines: VerificationPolicy regex pattern bypass via substring matching

Tekton Pipelines project provides k8s-style resources for declaring CI/CD-style pipelines. Starting in version 0.43.0 and prior to versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1, trusted resources verification policies match a resource source string refSource.URI against spec.resources.pattern...

CVE-2026-25542

Tekton Pipelines CVE-2026-25542 affects versions 0.43.0–1.11.0. The vulnerability arises because trusted resources verification policies compare refSource.URI against spec.resources[].pattern using Go’s regexp.MatchString, which reports a match if the pattern appears anywhere in the string. Unanc...

CVE-2026-27656

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to properly validate user identity in the OpenID IsSameUser comparison logic, which allows an attacker to take over arbitrary user accounts via an overly permissive substring matching flaw in the user...

Incorrect Implementation of Authentication Algorithm

Overview github.com/mattermost/mattermost-server is an open source Slack-alternative in Golang and React. Affected versions of this package are vulnerable to Incorrect Implementation of Authentication Algorithm in the IsSameUser function. An attacker can gain unauthorized access to arbitrary user...

GHSA-FG35-5RF6-QG3G Mattermost allows attackers to take over arbitrary user accounts via overly permissive substring matching flaw

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to properly validate user identity in the OpenID IsSameUser comparison logic, which allows an attacker to take over arbitrary user accounts via an overly permissive substring matching flaw in the user...

CVE-2026-27656

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to properly validate user identity in the OpenID IsSameUser comparison logic, which allows an attacker to take over arbitrary user accounts via an overly permissive substring matching flaw in the user...

CVE-2026-27656

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to properly validate user identity in the OpenID IsSameUser comparison logic, which allows an attacker to take over arbitrary user accounts via an overly permissive substring matching flaw in the user...