CVE-2026-42533
published 2026-07-15CVE-2026-42533: 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…
PriorityP355high8.1CVSS 3.1
AVNACHPRNUINSUCHIHAH
EPSS
0.83%
53.5th percentile
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
6 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| f5 | nginx_open_source | >= 0.9.6 < 1.30.4 | 1.30.4 |
| f5 | nginx_open_source | >= 1.31.2 < 1.31.3 | 1.31.3 |
| f5 | nginx_plus | — | — |
| f5 | nginx_plus | >= 37.0.0.1 < 37.0.3.1 | 37.0.3.1 |
| f5 | nginx_plus | >= R33 < * | * |
| f5 | nginx_plus | >= R36 < R36 P7 | R36 P7 |
CVSS provenance
nvdv3.18.1HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv4.09.2CRITICALCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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GHSA
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 outp
ghsa_unreviewed·2026-07-15
CVE-2026-42533 [CRITICAL] CWE-122 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 outp
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 (
F5
CVE-2026-42533: A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a string expr...
vendor_f5·2026-07-15·CVSS 8.1
CVE-2026-42533 [HIGH] CWE-122 CVE-2026-42533: A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a string expr...
CVE-2026-42533: A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a string expr...
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 (
No detection rules found.
No public exploits indexed.
2026-07-15
Published