F5 NGINX Plus/NGINX Open Source Map Directive heap-based overflow

Summaryinfo

A vulnerability marked as critical has been reported in F5 NGINX Plus and NGINX Open Source. This affects an unknown part of the component Map Directive. The manipulation leads to heap-based overflow. This vulnerability is uniquely identified as CVE-2026-93479. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in F5 NGINX Plus and NGINX Open Source (the affected version is unknown) and classified as critical. This issue affects an unknown code of the component Map Directive. The manipulation with an unknown input leads to a heap-based overflow vulnerability. Using CWE to declare the problem leads to CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). Impacted is confidentiality, integrity, and availability. The summary by CVE is:

A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and the root directive or access log format references the map's regex capture variables before referencing the map output variable. Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. 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; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

It is possible to read the advisory at my.f5.com. The identification of this vulnerability is CVE-2026-93479 since 09/30/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 10/14/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Web Server

Vendor

• F5

Name

• NGINX Open Source
• NGINX Plus

License

• commercial

Website

• Vendor: https://f5.com/

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CPE 2.2info

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Entryinfo

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