CVE-2026-101025: CWE-401 Missing Release of Memory after Effective Lifetime in F5 NGINX JavaScript
Description
F5 NGINX JavaScript (njs) contains a memory leak vulnerability in its built-in njs engine where the libxml2 parser context is not released if xml.parse() fails. An unauthenticated attacker can send malformed XML requests that cause unbounded memory growth in long-lived NGINX worker processes, potentially leading to worker termination or denial of service. This issue affects versions from 0.7.10 up to but not including 1.0.2. The vulnerability impacts availability only and does not expose control plane components.
CVSS v3.1
Score 5.3medium
Affected software
F5
NGINX JavaScript
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in F5 NGINX JavaScript (njs) arises from a missing release of memory (CWE-401) in the libxml2 parser context when xml.parse() fails. The failure path lacks proper cleanup, causing the parser context to remain allocated for the lifetime of the process. This memory leak can be triggered remotely by unauthenticated attackers sending malformed XML requests, leading to unbounded memory growth in NGINX worker processes. The affected versions are >=0.7.10 and <1.0.2. The CVSS v3.1 base score is 5.3, indicating a medium severity denial of service vulnerability affecting availability only.
Potential Impact
Remote attackers can cause unbounded memory growth in NGINX worker processes by sending malformed XML requests that trigger the memory leak. This can lead to termination of NGINX worker processes or denial of service. There is no impact on confidentiality or integrity, and no control plane exposure is involved.
Mitigation Recommendations
No official patch or remediation link is provided in the available data. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, consider limiting exposure to untrusted XML inputs or applying other protective measures as recommended by the vendor once an advisory is published.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- f5
- Date Reserved
- 2026-09-30T21:56:14.628Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6acf966f2cdf04f6568bce06
Added to database: 10/14/2026, 14:49:19 UTC
Last enriched: 10/14/2026, 15:03:59 UTC
Last updated: 10/14/2026, 15:08:25 UTC
Views: 6
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