CVE-2026-57236
Description
A flaw was found in Nokogiri, an XML and HTML library for Ruby. When an attacker provides an invalid encoding to the Document#encoding= function, the library frees the document's current encoding string without replacing it. This leaves the document referencing freed memory, which can lead to a denial of service (DoS) due to a segmentation fault or information disclosure by leaking freed memory into a Ruby String.
Statement
This flaw has an Important impact as Nokogiri's CRuby implementation in Red Hat products is vulnerable to a use-after-free when processing invalid encoding values. A remote unauthenticated attacker can trigger a segmentation fault causing denial of service, or leak freed memory contents into a Ruby String causing information disclosure, by providing crafted input that causes an invalid encoding to be set on a document.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
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 | 6.5 | 8.2 | N/A |
| Attack Vector | Network | 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 | Low | Low | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Red Hat CVSS v3 Score Explanation
Corrected AC:L to AC:H per upstream advisory: exploitation requires unusual API-usage pattern (attacker-controlled encoding, rescue exception, reuse document) that does not arise in normal use.
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
If the expired pointer is used in a read operation, an attacker might be able to control data read in by the application.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the expired pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the expired pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
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