Affected: AlmaLinux:8: expat, AlmaLinux:8: expat-devel

Expat is a C library for parsing XML documents.

Security Fix(es):

* expat: Expat: Denial of Service via quadratic complexity in attribute processing (CVE-2026-66046) * expat: Expat: XML Injection via Malformed UTF-16 Input (CVE-2026-93990)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Affected: Alpaquita:23: expat, Alpaquita:25: expat, Alpaquita:stream: expat, BellSoft Hardened Containers:23: expat, BellSoft Hardened Containers:25: expat, BellSoft Hardened Containers:stream: expat

Expat before 2.8.5 fails to validate that a high surrogate in UTF-16 input is followed by a low surrogate, allowing malformed UTF-16 sequences to be accepted. Attackers can supply UTF-16 encoded XML containing lone high surrogates that consume the following code unit, causing Expat to pass unpaired surrogates to applications built with XML_UNICODE and to silently replace input characters in other builds.

Expat through 2.8.4 fails to validate low surrogates following high surrogates in UTF-16 input, allowing malformed UTF-16 sequences to be accepted. Attackers can craft UTF-16 encoded XML with lone high surrogates that consume following code units, hiding markup characters from the parser and enabling XML injection attacks.

Affected: openEuler:22.03-LTS-SP4: expat

expat is a stream-oriented XML parser library written in C. expat excels with files too large to fit RAM, and where performance and flexibility are crucial. Security Fix(es):

Expat through 2.8.4 fails to validate low surrogates following high surrogates in UTF-16 input, allowing malformed UTF-16 sequences to be accepted. Attackers can craft UTF-16 encoded XML with lone high surrogates that consume following code units, hiding markup characters from the parser and enabling XML injection attacks.(CVE-2026-93990)

expat: Expat: XML Injection via Malformed UTF-16 Input

expat: Expat: Denial of Service via quadratic complexity in attribute processing expat: Expat: XML Injection via Malformed UTF-16 Input

Affected: Rocky Linux:8: expat

Expat is a C library for parsing XML documents.

Security Fix(es):

* expat: Expat: Denial of Service via quadratic complexity in attribute processing (CVE-2026-66046)

* expat: Expat: XML Injection via Malformed UTF-16 Input (CVE-2026-93990)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Affected: Ubuntu:Pro:14.04:LTS: coin3, Ubuntu:Pro:14.04:LTS: expat, Ubuntu:Pro:14.04:LTS: vnc4, Ubuntu:Pro:14.04:LTS: vtk, Ubuntu:Pro:14.04:LTS: xmlrpc-c, Ubuntu:Pro:16.04:LTS: expat, Ubuntu:Pro:16.04:LTS: ayttm, Ubuntu:Pro:16.04:LTS: cableswig, Ubuntu:16.04:LTS: cadaver, Ubuntu:Pro:16.04:LTS: coin3 and 57 more

Expat before 2.8.5 fails to validate that a high surrogate in UTF-16 input is followed by a low surrogate, allowing malformed UTF-16 sequences to be accepted. Attackers can supply UTF-16 encoded XML containing lone high surrogates that consume the following code unit, causing Expat to pass unpaired surrogates to applications built with XML_UNICODE and to silently replace input characters in other builds.

Ein entfernter, anonymer Angreifer kann eine Schwachstelle in expat ausnutzen, um Daten zu manipulieren.