CVE-2026-8711: CWE-122 Heap-based Buffer Overflow in F5 NGINX JavaScript
CVE-2026-8711 is a heap-based buffer overflow vulnerability in F5 NGINX JavaScript version 0. 9. 4. It occurs when the js_fetch_proxy directive is configured with at least one client-controlled NGINX variable and a location invokes the ngx. fetch() operation. An unauthenticated attacker can exploit this by sending crafted HTTP requests, potentially causing the NGINX worker process to restart. On systems without ASLR enabled, this vulnerability may allow code execution. The vulnerability has a high severity score of 8. 1. No official patch or remediation guidance has been provided yet.
AI Analysis
Technical Summary
F5 NGINX JavaScript 0.9.4 contains a heap-based buffer overflow (CWE-122) triggered when the js_fetch_proxy directive uses client-controlled variables such as $http_*, $arg_*, or $cookie_*, combined with ngx.fetch() calls. This flaw allows unauthenticated attackers to send specially crafted HTTP requests that overflow heap buffers in the NGINX worker process, causing it to restart. If Address Space Layout Randomization (ASLR) is disabled on the system, the vulnerability can lead to arbitrary code execution. The vulnerability is publicly disclosed with a CVSS 3.1 base score of 8.1, indicating high severity. There is no vendor-provided patch or official remediation level at this time, and the affected version is 0.9.4.
Potential Impact
Successful exploitation can cause denial of service by crashing and restarting the NGINX worker process. On systems without ASLR, exploitation may lead to remote code execution, allowing attackers to execute arbitrary code with the privileges of the NGINX process. This presents a significant risk to the confidentiality, integrity, and availability of affected systems.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid configuring js_fetch_proxy with client-controlled variables or disable the affected functionality if possible. Monitor vendor communications for updates on patches or official mitigations.
CVE-2026-8711: CWE-122 Heap-based Buffer Overflow in F5 NGINX JavaScript
Description
CVE-2026-8711 is a heap-based buffer overflow vulnerability in F5 NGINX JavaScript version 0. 9. 4. It occurs when the js_fetch_proxy directive is configured with at least one client-controlled NGINX variable and a location invokes the ngx. fetch() operation. An unauthenticated attacker can exploit this by sending crafted HTTP requests, potentially causing the NGINX worker process to restart. On systems without ASLR enabled, this vulnerability may allow code execution. The vulnerability has a high severity score of 8. 1. No official patch or remediation guidance has been provided yet.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
F5 NGINX JavaScript 0.9.4 contains a heap-based buffer overflow (CWE-122) triggered when the js_fetch_proxy directive uses client-controlled variables such as $http_*, $arg_*, or $cookie_*, combined with ngx.fetch() calls. This flaw allows unauthenticated attackers to send specially crafted HTTP requests that overflow heap buffers in the NGINX worker process, causing it to restart. If Address Space Layout Randomization (ASLR) is disabled on the system, the vulnerability can lead to arbitrary code execution. The vulnerability is publicly disclosed with a CVSS 3.1 base score of 8.1, indicating high severity. There is no vendor-provided patch or official remediation level at this time, and the affected version is 0.9.4.
Potential Impact
Successful exploitation can cause denial of service by crashing and restarting the NGINX worker process. On systems without ASLR, exploitation may lead to remote code execution, allowing attackers to execute arbitrary code with the privileges of the NGINX process. This presents a significant risk to the confidentiality, integrity, and availability of affected systems.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid configuring js_fetch_proxy with client-controlled variables or disable the affected functionality if possible. Monitor vendor communications for updates on patches or official mitigations.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- f5
- Date Reserved
- 2026-05-15T20:10:29.764Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a0c757aec166c07b0b402b4
Added to database: 5/19/2026, 2:36:42 PM
Last enriched: 5/19/2026, 2:51:38 PM
Last updated: 5/19/2026, 3:51:35 PM
Views: 3
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