CVE-2026-86143
Description
An integer overflow in the libxml2 xmlIO module occurs when data backlogs exceed maximum integer limits. This flaw passes negative length values to downstream write callbacks, creating an unsafe state that can lead to data corruption or compromise application confidentiality and integrity.
Statement
Moderate impact: This flaw in libxml2, a widely used XML parsing library, is due to an integer overflow in write callbacks. This can lead to negative lengths being passed to write operations, potentially causing data integrity issues in applications that process untrusted XML input and utilize affected write callbacks. The impact is limited to applications that specifically trigger this overflow condition.
Mitigation
Cap process and cgroup memory so a process cannot build a ≥2 GiB libxml2 output backlog. Keep FORTIFY_SOURCE-built Red Hat binaries so some callback copies of the truncated length abort instead of corrupting memory
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.9 | N/A | 6.9 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | Low | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
cve.org: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Crash, Exit, or Restart
Integer coercion often leads to undefined states of execution resulting in infinite loops or crashes.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
In some cases, integer coercion errors can lead to exploitable buffer overflow conditions, resulting in the execution of arbitrary code.
Integrity,Other
Technical Impact: Other
Integer coercion errors result in an incorrect value being stored for the variable in question.
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