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CVE-2026-40701

MEDIUMCVSS 6.3/10EPSS 0.68%

Last modified

CVE-2026-40701 is a medium-severity vulnerability rated 6.3/10 on the CVSS scale. NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssl_module module when the ssl_verify_client directive is set to "on" or "optional," and the ssl_ocsp directive is set to "on" or the leaf parameters are configured with a resolver. With this configuration, an unauthenticated attacker can send requests along with conditions beyond its control that may cause a heap-use-after-free error in the NGINX worker process. EPSS estimates a 0.68% chance of exploitation in the next 30 days.

Description

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssl_module module when the ssl_verify_client directive is set to "on" or "optional," and the ssl_ocsp directive is set to "on" or the leaf parameters are configured with a resolver. With this configuration, an unauthenticated attacker can send requests along with conditions beyond its control that may cause a heap-use-after-free error in the NGINX worker process. This vulnerability may result in limited modification of data or the NGINX worker process restarting.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Metrics

CVSS 3.1
4.8/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L

CVSS 4.0
6.3/10

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/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

EPSS Probability
0.68%

47.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
F5Dos>= 4.3.0, <= 4.7.0
F5Dos4.8.0
F5Nginx Gateway Fabric>= 1.3.0, <= 1.6.2
F5Nginx Gateway Fabric>= 2.0.0, <= 2.6.0
F5Nginx Ingress Controller>= 3.5.0, <= 3.7.2
F5Nginx Ingress Controller>= 4.0.0, <= 4.0.1
F5Nginx Ingress Controller>= 5.0.0, <= 5.4.2
F5Nginx Instance Manager>= 2.16.0, <= 2.22.0
F5Nginx Open Source>= 1.19.0, <= 1.30.0
F5Nginx Plus>= r32, <= r36
F5Waf>= 4.9.0, <= 4.16.0
F5Waf>= 5.1.0, <= 5.8.0
F5Waf>= 5.9.0, <= 5.12.1

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-40701?
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssl_module module when the ssl_verify_client directive is set to "on" or "optional," and the ssl_ocsp directive is set to "on" or the leaf parameters are configured with a resolver. With this configuration, an unauthenticated attacker can send requests along with conditions beyond its control that may cause a heap-use-after-free error in the NGINX worker process. This vulnerability may result in limited modification of data or the NGINX worker process restarting.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
How severe is CVE-2026-40701?
CVE-2026-40701 has a CVSS score of 6.3/10 (MEDIUM severity). The EPSS model estimates a 0.68% probability of exploitation in the next 30 days.
How do I fix CVE-2026-40701?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-40701?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST