CVE-2026-42533

NGINX Map directive and Regex matching vulnerability

HIGH

8.1

CVSS Score

Published: July 15, 2026 at 02:33 PM UTC

Updated: August 10, 2026 at 03:38 PM UTC

5 products affected across 1 vendorNGINX PlusNGINX Ingress ControllerNGINX Gateway Fabric

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Severity

HIGH8.1

Exploit prediction

EPSS 0.9%

SSVC

PoC

Description

A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a string expression 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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

NGINX Gateway Fabric · F5

95%

1.3.0 ≤ v ≤ 1.6.22.0.0 ≤ v < 2.6.7

Affected range stops below 2.6.7, so it looks safe — our inference, not a vendor statement

NGINX Ingress Controller · F5

95%

2026-lts-r1 ≤ v < 2026-lts-r43.5.0 ≤ v ≤ 3.7.25.0.0 ≤ v < 5.5.34.0.0 4.0.1

Affected range stops below 2026-lts-r4, so it looks safe — our inference, not a vendor statement

Affected range stops below 5.5.3, so it looks safe — our inference, not a vendor statement

NGINX Plus · F5

95%

v ≥ R3337.0.0.1 ≤ v < 37.0.3.1R36 ≤ v < R36 P7r33 ≤ v < r3637.0.0.1 R33 R36 r36 r36 p1 r36 p2 r36 p3 r36 p4 r36 p5 r36 p6

Affected range stops below 37.0.3.1, so it looks safe — our inference, not a vendor statement

Affected range stops below R36 P7, so it looks safe — our inference, not a vendor statement

Affected range stops below r36, so it looks safe — our inference, not a vendor statement

Waf · F5

95%

4.11.0 ≤ v ≤ 4.16.05.2.0 ≤ v ≤ 5.8.05.9.0 ≤ v < 5.13.4

Affected range stops below 5.13.4, so it looks safe — our inference, not a vendor statement

NGINX Open Source · F5

60%

0.9.6 ≤ v < 1.30.41.31.2 ≤ v < 1.31.30.9.6 1.31.2

Affected range stops below 1.30.4, so it looks safe — our inference, not a vendor statement

Affected range stops below 1.31.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://my.f5.com/manage/s/article/K000162097

References (1)

Vendor AdvisoryPatch

Source: cverecord

https://my.f5.com/manage/s/article/K000162097

SSVC — Action Prioritization

SSVCPoCNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.1HIGHf5

Attack Vector: NETWORK
Complexity: HIGH
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: HIGH
Availability: HIGH

Vector?

Quick Info

StatusANALYZED

CWE

CWE-122

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