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CVE-2026-93479

NGINX map directive and regex matching vulnerability

  • Critical 9.2

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.

Key facts

Published
14 Oct 2026
Last changed
29 Oct 2026
Assigned by
f5
EPSS
1.198% likely to be exploited in the next 30 days, higher than 68.626% of CVEs (scores for 15 Nov 2026)
SSVC (CISA)
Exploitation: none; Automatable: no; Technical impact: total

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

  • 8.1CVSS 3.1, Highfrom the CNA (f5)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
  • 9.2CVSS 4.0, Criticalfrom the CNA (f5)CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

What to do

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

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

CAPEC-100 Overflow Buffers (CNA impact statement)

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

VendorProductVersions
F5NGINX Plus
  • Default status: unknown
  • 37.1.0 up to but excluding 37.1.0.1 (affected)
  • 37.0.0 up to but excluding 37.0.5.1 (affected)
  • R36 up to but excluding * (affected)
  • R35 up to but excluding * (affected)
  • R34 up to but excluding * (affected)
  • R33 up to but excluding * (affected)
F5NGINX Open Source
  • Default status: unaffected
  • 1.31.2 up to but excluding 1.31.7 (affected)
  • 1.30.0 up to but excluding 1.30.6 (affected)

Timeline

  1. 14 Oct 2026 Published

Weakness

Related coverage

References