CVE-2026-42533
highpriority · track · 10EPSS 0.009 · 59 %ileexploit · PoCDEEURUUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 8.1–9.2
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
exploits (12)
Public proof-of-concept and weaponised exploit code.
- Leeyoonjoo/CVE-2026-42533Leeyoonjoo/CVE-2026-42533PoC · poc_in_github
- gagaltotal/CVE-2026-42533-nginxCVE-2026-42533 NginxPoC · poc_in_github
affected products (66)
Products and version ranges known to be affected.
advisories (3)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-2383NGINX NGINX Plus: Mehrere SchwachstellenDeutsch2026-07-15csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in NGINX NGINX Plus ausnutzen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, um Daten zu manipulieren, und um Informationen offenzulegen.
- BIT-nginx-2026-42533NGINX Map directive and Regex matching vulnerability2026-07-20vendor · osvUS
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.
- BIT-nginx-gateway-2026-42533NGINX Map directive and Regex matching vulnerability2026-07-20vendor · osvUS
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.
also known as (6)
Other names and identifiers for this entity.
- CNNVD-2026-44222803cnnvd
- EUVD-2026-44683enisa_euvd
- BDU:2026-09927fstec_bdu
- GHSA-fxfg-v4rj-hp95enisa_euvd
- BIT-nginx-2026-42533osv
- BIT-nginx-gateway-2026-42533osv
sources
Which sources assert this record, and when.
references (3)
External citations — patches, advisories, analysis.
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