NGINX map directive and regex matching vulnerability

Description

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.

Timeline

Scores

EPSS (exploitation in 30 days)

1.2% · top 32% of all CVEs (7 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: total

The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.2.

Weakness

• CWE-122 Heap-based Buffer Overflow (opens in a new tab)All about CWE-122 and its CVEs

Affected products

• F5 · NGINX Plus

  • affected 37.1.0 – < 37.1.0.1
  • affected 37.0.0 – < 37.0.5.1
  • affected R36 – < *
  • affected R35 – < *
  • affected R34 – < *
  • affected R33 – < *

• F5 · NGINX Open Source

  • affected 1.31.2 – < 1.31.7
  • affected 1.30.0 – < 1.30.6

What to do

Workaround: To mitigate this vulnerability, do not use unnamed captures. Use named captures instead and limit their usage to the block with the regex match.

References (1)

• https://my.f5.com/manage/s/article/K000162607 (opens in a new tab)vendor-advisory

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-93479](https://trackcve.app/badge/CVE-2026-93479.svg)](https://trackcve.app/cve/CVE-2026-93479)

Record last updated 29 Oct 2026, 16:59 UTC.