High-Severity Heap-Based Buffer Overflow Flaw in F5 NGINX Plus Tracked as CVE-2026-15176
A newly published high vulnerability in F5 NGINX Plus carries a CVSS score of 8.1. Here is what is affected and how to respond.
Key points
- CVE-2026-15176 affects F5 NGINX Plus.
- CVSS 8.1 (High).
- No exploitation confirmed yet.
A high heap-based buffer overflow tracked as CVE-2026-15176 has been published in the National Vulnerability Database for F5 NGINX Plus, with a CVSS base score of 8.1.
At a glance
- CVE
- CVE-2026-15176
- Product
- F5 NGINX Plus
- CVSS
- 8.1 High
- Weakness
- heap-based buffer overflow
- Exploited
- No known exploitation
What is the vulnerability?
The NVD entry states: A vulnerability exists in NGINX Plus and NGINX Open Source when a location is configured that uses the alias directive together with rewrite and a set or return directive referencing the $request_filename variable. Alternatively, the same result could be achieved when the $request_filename variable is used in an access log format directive. An unauthenticated attacker along with conditions beyond their control 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.
Impact:
This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure;
Affected versions
| Vendor | Product | Versions |
|---|---|---|
| F5 | NGINX Plus | before 37.1.0.1, before 37.0.5.1, before *, before * |
| F5 | NGINX Open Source | before 1.31.7, before 1.30.6 |
CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
Is it being exploited?
There is no public confirmation of exploitation at the time of publication. It does not appear in CISA's Known Exploited Vulnerabilities catalog. We will update this report if that changes.
What should you do?
- Identify whether the affected product and versions run in your environment.
- Apply the vendor update listed in the advisory as soon as it is available.
- Limit network exposure of the affected service until it is patched.
- Monitor the vendor advisory for updated guidance or exploitation reports.
What to do and how to stay safe: CVE-2026-15176
- Vulnerability severity scores ignore your specific architecture and context.
- Exploitability depends on network exposure and user behavior, not just code flaws.
- Prioritization requires continuous asset inventory and threat intelligence alignment.
Risk-based vulnerability management focuses your limited resources on the flaws that actually threaten your business. Start by mapping your critical assets and checking for active exploits to prioritize your backlog.
Step-by-step guide: Risk-Based Vulnerability Management: Prioritize Fixes by Actual Danger
General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
What is CVE-2026-15176?
CVE-2026-15176 is a heap-based buffer overflow vulnerability in F5 NGINX Plus.
How severe is CVE-2026-15176?
It has a CVSS score of 8.1 High.
Is CVE-2026-15176 being exploited?
There is no public confirmation of exploitation at the time of publication.
