SB2026012788 - Ubuntu update for libxml2

Description

This security bulletin contains information about 4 secuirty vulnerabilities.

1) Infinite loop (CVE-ID: CVE-2025-8732)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to infinite loop within the xmlParseSGMLCatalog() function in catalog.c when parsing untrusted SGML catalogs. A remote attacker can trick the victim into passing a specially crafted SGML catalogs to the application and perform a denial of service (DoS) attack.

2) Uncontrolled Recursion (CVE-ID: CVE-2026-0989)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to an uncontrolled recursion in the RelaxNG parser. A remote attacker can pass specially crafted input to the application and perform a denial of service attack.

3) Uncontrolled Recursion (CVE-ID: CVE-2026-0990)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to an uncontrolled recursion in the xmlCatalogXMLResolveURI function when an XML catalog contains a delegate URI entry that references itself. A remote attacker can pass specially crafted input to the application and perform a denial of service attack.

4) Resource exhaustion (CVE-ID: CVE-2026-0992)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to application does not properly control consumption of internal resources when processing XML catalogs that contain repeated <nextCatalog> elements pointing to the same downstream catalog. A remote attacker can trigger resource exhaustion and perform a denial of service (DoS) attack.

Remediation

Install update from vendor's website.

References

• https://ubuntu.com/security/notices/USN-7974-1