SB2026012788 - Ubuntu update for libxml2

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Main Vulnerability Database SB2026012788

SB2026012788 - Ubuntu update for libxml2

Published: January 27, 2026

Security Bulletin ID SB2026012788
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 4
Exploitation vector Remote access
Highest impact Denial of service

Breakdown by Severity

Medium 75% Low 25%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 4 vulnerabilities.


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

CWE-ID: CWE-835 - Loop with Unreachable Exit Condition ('Infinite Loop')

CVSSv4: CVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear


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)

CWE-ID: CWE-674 - Uncontrolled Recursion

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Green


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)

CWE-ID: CWE-674 - Uncontrolled Recursion

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green


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)

CWE-ID: CWE-400 - Resource exhaustion

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green


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