Vulnerability details
CVE-2026-8711
F5 NGINX JavaScript
NGINX JavaScript vulnerability
CVSS 4.0
9.2Critical
Official description
NGINX JavaScript has a vulnerability when the js_fetch_proxy directive is configured with at least one client-controlled NGINX variable (for example, $http_*, $arg_*, $cookie_*) and a location invoking the ngx.fetch() operation from NGINX JavaScript. An unauthenticated attacker can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 9.2Critical | 4.0 | CVEProject cvelistV5 (CNA) (f5) | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
| 8.1High | 3.1 | CVEProject cvelistV5 (CNA) (f5) | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| F5 | NGINX JavaScript | 0.9.4 ≤ v < 0.9.9 | CVEProject cvelistV5 (CNA) |
References and advisories
1- https://my.f5.com/manage/s/article/K000161307 vendor-advisory
Kolun on Telegram @kolunsec
Exploited CVEs, key news and a daily digest
Alerts for this product's next CVEsFollow the product to get new vulnerabilities on Telegram.
Details
- Published
- 2026-05-19
- Last updated
- 2026-05-21
- State
- Published
- Assigner (CNA)
- f5
Exploit prediction (EPSS)
9.68%
Probability of exploitation in 30 days
95.5%
Percentile (among all CVEs)
SSVC assessment (CISA)
- Automatable
- No
- Exploitation
- None
- Technical impact
- Total
Weaknesses (CWE)
- CWE-122Heap-based Buffer Overflow