When an Expat parser with a registered ElementDeclHandler parses an inline document type definition containing a deeply nested content model a C stack overflow occurs.

Mattermost versions 10.11.x <= 10.11.10 fail to validate user's authentication method when processing account auth type switch which allows an authenticated attacker to change account password without confirmation via falsely claiming a different auth provider.. Mattermost Advisory ID: MMSA-2026-00583

HCL AION is affected by a vulnerability where model packaging and distribution mechanisms may not include sufficient authenticity verification. This may allow the possibility of unverified or modified model artifacts being used, potentially leading to integrity concerns or unintended behaviour.

HCL AION is affected by a vulnerability related to the handling of upload size limits. Improper control or validation of upload sizes may allow excessive resource consumption, which could potentially lead to service degradation or denial-of-service conditions under certain scenarios.

The fix for CVE-2026-0672, which rejected control characters in http.cookies.Morsel, was incomplete. The Morsel.update(), |= operator, and unpickling paths were not patched, allowing control characters to bypass input validation. Additionally, BaseCookie.js_output() lacked the output validation applied to BaseCookie.output().

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to bound memory allocation when processing DOC files which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted DOC file.. Mattermost Advisory ID: MMSA-2026-00581

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to validate team-specific upload_file permissions which allows a guest user to post files in channels where they lack upload_file permission via uploading files in a team where they have permission and reusing the file metadata in a POST request to a different team. Mattermost Advisory ID: MMSA-2025-00553

HCL AION is affected by a vulnerability where certain user actions are not adequately audited or logged. The absence of proper auditing mechanisms may reduce traceability of user activities and could potentially impact monitoring, accountability, or incident investigation processes.

HCL AION is affected by a vulnerability where internal filesystem paths may be exposed through application responses or system behaviour. Exposure of internal paths may reveal environment structure details which could potentially aid in further targeted attacks or information disclosure.

Webhooks for Craft CMS plugin adds the ability to manage “webhooks” in Craft CMS, which will send GET or POST requests when certain events occur. From version 3.0.0 to before version 3.2.0, the Webhooks plugin renders user-supplied template content through Twig’s renderString() function without sandbox protection. This allows an authenticated user with access to the Craft control panel and permissions to access the Webhooks plugin to inject Twig template code that calls arbitrary PHP functions. This is possible even if allowAdminChanges is set to false. This issue has been patched in version 3.2.0.