CVE-2026-41401
Description
A flaw was found in libyang. This heap use-after-free write vulnerability, specifically within the lyd_parser_set_data_flags function, occurs when the software incorrectly updates metadata list pointers during the freeing of non-head default metadata entries. A remote attacker can exploit this by submitting specially crafted YANG XML documents containing specific metadata attributes to applications that parse untrusted XML data. Successful exploitation could lead to application process to crash.
Statement
This vulnerability affects applications using libyang to process XML-encoded YANG data. Red Hat Product Security has assessed this issue as a Moderate severity vulnerability.
An authenticated attacker may supply specially crafted YANG/XML input that triggers a heap use-after-free condition during metadata parsing operations, resulting in application crashes and denial of service.
Although the vulnerability involves heap memory corruption, the current analysis and reproductions demonstrate denial-of-service impact through application crashes rather than reliable arbitrary code execution. Red Hat therefore assessed the impact as limited to Availability (A:H).
Because exploitation generally requires the ability to submit or process crafted YANG configuration data, Red Hat assessed Privileges Required as Low (PR:L).
Mitigation
Red Hat is not aware of a practical temporary workaround that fully mitigates this issue or meets Red Hat Product Security's standards for usability, deployment, applicability, 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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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