Answer in brief
CVE-2026-42533 records a High severity (CVSS 8.1) vulnerability in NGINX Map directive and Regex matching vulnerability. The current sources do not mark it as known exploited. The current feed maps F5/NGINX Open Source (generic), F5/NGINX Plus (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps F5/NGINX Open Source (generic), F5/NGINX Plus (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| F5/NGINX Open Sourcegeneric | >=1.31.2 <1.31.3 || >=0.9.6 <1.30.4 | 1.31.3, 1.30.4 |
| F5/NGINX Plusgeneric | >=37.0.0.1 <37.0.3.1 || >=R36 <R36 P7 || >=R33 <* | 37.0.3.1, R36 P7, * |
Published upstream
Jul 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 29, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 15, 2026
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.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-42533 records a High severity (CVSS 8.1) vulnerability in NGINX Map directive and Regex matching vulnerability. The current sources do not mark it as known exploited. The current feed maps F5/NGINX Open Source (generic), F5/NGINX Plus (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps F5/NGINX Open Source (generic), F5/NGINX Plus (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| F5/NGINX Open Sourcegeneric | >=1.31.2 <1.31.3 || >=0.9.6 <1.30.4 | 1.31.3, 1.30.4 |
| F5/NGINX Plusgeneric | >=37.0.0.1 <37.0.3.1 || >=R36 <R36 P7 || >=R33 <* | 37.0.3.1, R36 P7, * |
Published upstream
Jul 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 29, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 15, 2026
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.
Quoted source text, attributed separately from HOL analysis.