Security Bulletin: IBM App Connect Enterprise Certified Container DesignerAuthoriong operands are vulnerable to cross-site scripting (GHSA-h8r8-wccr-v5f2, GHSA-cjmm-f4jc-qw8r) and prototype polution (GHSA-cj63-jhhr-wcxv)

Vulnerability Details

ID:   GHSA-h8r8-wccr-v5f2
DESCRIPTION:   A mutation-XSS (mXSS) condition was confirmed when sanitized HTML is reinserted into a new parsing context using innerHTML and special wrappers. The vulnerable wrappers confirmed in browser behavior are script, xmp, iframe, noembed, noframes, and noscript. The payload remains seemingly benign after DOMPurify.sanitize(), but mutates during the second parse into executable markup with an event handler, enabling JavaScript execution in the client (alert(1) in the PoC).
CWE:   CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVSS Source:   GitHub
CVSS Base score:   6.9
CVSS Vector:   (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N)

ID:   GHSA-cjmm-f4jc-qw8r
DESCRIPTION:   DOMPurify allows ADD_ATTR to be provided as a predicate function via EXTRA_ELEMENT_HANDLING.attributeCheck. When the predicate returns true, _isValidAttribute short-circuits the attribute check before URI-safe validation runs. An attacker who supplies a predicate that accepts specific attribute/tag combinations can then sanitize input such as <a href="javascript:alert(document.domain)"> and have the javascript: URL survive, because URI validation is skipped for that attribute while other checks still pass. The provided PoC accepts href for anchors and then triggers a click inside an iframe, showing that the sanitized payload executes despite the protocol bypass.

 
CWE:   CWE-183: Permissive List of Allowed Inputs
CVSS Source:   GitHub
CVSS Base score:   5.3
CVSS Vector:   (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N)

ID:   GHSA-cj63-jhhr-wcxv
DESCRIPTION:   When USE_PROFILES is enabled, DOMPurify rebuilds ALLOWED_ATTR as a plain array before populating it with the requested allowlists. Because the sanitizer still looks up attributes via ALLOWED_ATTR[lcName], any Array.prototype property that is polluted also counts as an allowlisted attribute. An attacker who can set Array.prototype.onclick = true (or a runtime already subject to prototype pollution) can thus force DOMPurify to keep event handlers such as onclick even when they are normally forbidden. The provided PoC sanitizes <img onclick=...> with USE_PROFILES and adds the sanitized output to the DOM; the polluted prototype allows the event handler to survive and execute, turning what should be a blocklist into a silent XSS vector.
CWE:   CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
CVSS Source:   GitHub
CVSS Base score:   5.3
CVSS Vector:   (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N)