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CVE-2026-8711

⚠️ high
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Summary

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 Spa

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 Score
8.1
High
EPSS Score
0.1
Exploit Probability
Published Date
2026-05-19
First Seen: 2026-05-20
📊 Relative Risk Intelligence

This CVE is High Risk - more severe than 77.5% of all 326,604 vulnerabilities in our database.

#73,427
Top 25% most severe
Severity Percentile
🎯 CISA SSVC Assessment Updated: May 19, 2026
🔍 Exploitation Status
None
No known exploits
⚙️ Automatable
NO
Requires human interaction
💥 Technical Impact
Total
Complete system compromise possible
🏆 Discovered By
"F5 acknowledges udolemi (S2W) for bringing this issue to our attention and following the highest standards of coordinated disclosure." (reporter)
SSVC data provided by CISA
Last Modified 2026-06-04
Source NVD 🔗
CVSS Vector 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Vector 4.0 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CWE IDs (Weakness Types)
CWE-122

📦 Affected Products 1

Vendor Product Status Affected Versions
f5 njs Affected
> 0.9.4 < 0.9.9

🔗 References 1

https://my.f5.com/manage/s/article/K000161307
Vendor Advisory

🔗 Related CVEs 6

CVE ID Severity CVSS EPSS Summary Published
CVE-2023-27727 ⚠️ high 7.5 0.1 Nginx NJS v0.7.10 was discovered to contain a segmentation violation via the function njs_function_frame at src/njs_func... 2023-04-09
CVE-2023-27728 ⚠️ high 7.5 0.1 Nginx NJS v0.7.10 was discovered to contain a segmentation violation via the function njs_dump_is_recursive at src/njs_v... 2023-04-09
CVE-2023-27729 ⚠️ high 7.5 0.1 Nginx NJS v0.7.10 was discovered to contain an illegal memcpy via the function njs_vmcode_return at src/njs_vmcode.c. 2023-04-09
CVE-2023-27730 ⚠️ high 7.5 0.1 Nginx NJS v0.7.10 was discovered to contain a segmentation violation via the function njs_lvlhsh_find at src/njs_lvlhsh.... 2023-04-09
CVE-2020-19692 ⛔ critical 9.8 1.3 Buffer Overflow vulnerabilty found in Nginx NJS v.0feca92 allows a remote attacker to execute arbitrary code via the njs... 2023-04-04
CVE-2020-19695 ⛔ critical 9.8 1.4 Buffer Overflow found in Nginx NJS allows a remote attacker to execute arbitrary code via the njs_object_property parame... 2023-04-04
These CVEs affect the same products