CVE-2026-57434
Description
A flaw was found in Nokogiri, an open source XML and HTML library for the Ruby programming language. A remote attacker could exploit this vulnerability by calling specific methods on allocated-but-uninitialized native wrapper classes that inherit from Nokogiri::XML::Node. This could lead to a NULL pointer dereference, causing the process to crash and resulting in a Denial of Service (DoS).
Statement
A flaw was found in Nokogiri, an open source XML and HTML library for Ruby. Calling certain methods on allocated-but-uninitialized native wrapper classes that inherit from Nokogiri::XML::Node triggers a NULL pointer dereference, crashing the process. An attacker who can control the construction of Nokogiri node objects could exploit this to cause a Denial of Service. The vulnerability is fixed in Nokogiri 1.19.4.
Mitigation
There is no mitigation for this flaw other than updating to Nokogiri version 1.19.4 or later. As a workaround, ensure that untrusted input cannot trigger the construction of uninitialized native wrapper classes inheriting from Nokogiri::XML::Node.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 2.9 | 7.5 | N/A |
| Attack Vector | Local | Network | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | Low | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Red Hat CVSS v3 Score Explanation
Downgraded: upstream confirms this requires .allocate misuse (programming error), not triggerable by untrusted input. AV:L — requires local code authoring the buggy pattern. AC:H — prerequisite of incorrect API usage. A:L — single-process crash.
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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