CVE-2026-8711

HIGHEPSS 95th pctl

8.1

CVSS v3

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.

CWE-122Heap-based Buffer Overflow

How to fix

Remediation Available

libnginx-mod-jsDebian

Fixed in:0.9.9-1CVE-2026-8711

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

9.69%probability of exploitation in 30 days

95thpercentile

Very high risk: more likely to be exploited than 95% of all known CVEs.

References

Vendor Advisory1

my.f5.com

Related Vulnerabilities

Other CWE-122 (Heap-based Buffer Overflow) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2015-3113	Critical	9.8	100%	KEV	Fix
CVE-2024-26256	High	7.8	88%	-	Fix
CVE-2020-25687	Medium	5.9	87%	-	Fix
CVE-2009-3459	High	8.8	87%	KEV	Fix
CVE-2021-21017	High	8.8	86%	KEV	-
CVE-2020-25683	Medium	5.9	86%	-	Fix

Common questions

How do I fix CVE-2026-8711?

Upgrade libnginx-mod-js on debian unstable to 0.9.9-1 or later.

Is CVE-2026-8711 being actively exploited?

Not that we know of. CVE-2026-8711 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 9.7% is the estimated probability that it will be exploited in the next 30 days. That is higher than 95% of all scored CVEs.

How severe is CVE-2026-8711?

CVE-2026-8711 has a CVSS v3 base score of 8.1, rated important. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-8711 affect?

Published advisories record a fix for libnginx-mod-js (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-23.