SB2026093020 - Ubuntu update for expat

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Main Vulnerability Database SB2026093020

SB2026093020 - Ubuntu update for expat

Published: September 30, 2026 Updated: September 30, 2026

Security Bulletin ID SB2026093020
CSH Severity
High
Patch available
YES
Number of vulnerabilities 11
Exploitation vector Remote access
Highest impact Code execution

Breakdown by Severity

High 9% Medium 91%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 11 vulnerabilities.


1) Integer overflow (CVE-ID: CVE-2026-56406)

CWE-ID: CWE-190 - Integer overflow

CVSSv4: 8.7 [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]


The vulnerability allows a remote attacker to cause memory corruption.

The vulnerability exists due to an integer overflow in XML_ParseBuffer when parsing buffered XML input. A remote attacker can supply crafted XML input to cause memory corruption.


2) Integer overflow (CVE-ID: CVE-2026-56407)

CWE-ID: CWE-190 - Integer overflow

CVSSv4: 8.7 [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]


The vulnerability allows a remote attacker to cause memory corruption.

The vulnerability exists due to an integer overflow in textLen handling when parsing XML data. A remote attacker can supply crafted XML input to cause memory corruption.


3) Integer overflow (CVE-ID: CVE-2026-56409)

CWE-ID: CWE-190 - Integer overflow

CVSSv4: 8.7 [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]


The vulnerability allows a remote attacker to cause memory corruption.

The vulnerability exists due to an integer overflow in the xmlwf output path join logic when joining output paths. A remote attacker can supply crafted input to cause memory corruption.

This issue affects the xmlwf tool.


4) Integer overflow (CVE-ID: CVE-2026-56410)

CWE-ID: CWE-190 - Integer overflow

CVSSv4: 8.7 [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]


The vulnerability allows a remote attacker to cause memory corruption.

The vulnerability exists due to an integer overflow in xmlwf resolveSystemId when resolving system identifiers. A remote attacker can supply crafted input to cause memory corruption.

This issue affects the xmlwf tool.


5) Integer overflow (CVE-ID: CVE-2026-56411)

CWE-ID: CWE-190 - Integer overflow

CVSSv4: 8.7 [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]


The vulnerability allows a remote attacker to cause memory corruption.

The vulnerability exists due to an integer overflow in xmlwf notation list allocation when allocating notation list memory. A remote attacker can supply crafted input to cause memory corruption.

This issue affects the xmlwf tool.


6) Protection mechanism failure (CVE-ID: CVE-2026-56131)

CWE-ID: CWE-693 - Protection Mechanism Failure

CVSSv4: 8.7 [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]


The vulnerability allows a remote attacker to cause memory corruption.

The vulnerability exists due to missing control flow integrity checks in XML_ResumeParser when it is called from a handler. A remote attacker can trigger a handler-driven call to XML_ResumeParser to cause memory corruption.

This issue is described as a hole in the fix for CVE-2026-50219.


7) Out-of-bounds write (CVE-ID: CVE-2026-56132)

CWE-ID: CWE-787 - Out-of-bounds write

CVSSv4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to cause memory corruption.

The vulnerability exists due to an out-of-bounds write in doProlog when processing scaffolding index data. A remote attacker can supply crafted XML input to cause memory corruption.


8) Out-of-bounds read (CVE-ID: CVE-2026-72522)

CWE-ID: CWE-125 - Out-of-bounds read

CVSSv4: 6.9 [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]


The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to a boundary condition during Unicode processing in the *_toUtf16 function. A remote attacker can pass specially crafted XML input to the application, trigger an infinite loop and perform a denial of service attack.


9) Inefficient Algorithmic Complexity (CVE-ID: CVE-2026-66046)

CWE-ID: CWE-407 - Inefficient Algorithmic Complexity

CVSSv4: 8.7 [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]


The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to algorithmic complexity in attribute declaration handling when parsing XML documents with numerous attributes. A remote attacker can submit a crafted XML document to cause a denial of service.


10) Inefficient Algorithmic Complexity (CVE-ID: CVE-2026-76641)

CWE-ID: CWE-407 - Inefficient Algorithmic Complexity

CVSSv4: 8.7 [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]


The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to an inefficient algorithm in attribute isCdata lookups when parsing crafted XML input. A remote attacker can submit moderately sized crafted XML input to cause a denial of service.

A compression layer around XML can significantly reduce the minimum attack payload size.


11) Use-after-free (CVE-ID: CVE-2026-76957)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 6.9 [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]


The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a lack of handler call depth tracking with custom encoding callbacks. A remote attacker can pass specially crafted XML input to the application, trigger a use-after-free error and perform a denial of service attack.


Remediation

Install update from vendor's website.

References