CVE-2026-40701: F5 NGINX Plus · Use After Free
Affects F5 NGINX PlusSource CVE Database V5
Not known to be exploited · CVSS 4.8 Medium : upgrade to 1.30.1 when convenient.
Data as of 29 Oct 2026, 19:04 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 52% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 1.30.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:LExploitation evidence
Disclosed: evidence found.
CVE published 13 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade NGINX Open Source to 1.30.1.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| F5NGINX Plus | Affected
| Fixed in– |
| F5NGINX Open Source | Affected
| Fixed in
|
AI-suggested
If you cannot patch yet, consider disabling ssl_ocsp or ssl_verify_client directives if feasible to avoid the vulnerable configuration.
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.