Auth bypass in F5 nginx
CVE-2025-23419
When multiple server blocks are configured to share the same IP address and port, an attacker can use session resumption to bypass client certificate authentication requirements on these servers. This vulnerability arises when TLS Session Tickets https://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_session_ticket_key are used and/or the SSL session cache https://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_session_cache are used in the default server and the default server is performing client certificate authentication. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.028 (85.9th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 86th percentile — 85.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.028 · newest: 0.028 · change: 0.000
Affected products
- F5 nginx
- F5 nginx Open Source — versions 1.11.4
- F5 nginx Plus — versions R17
- F5 nginx Plus — versions r32, r33
- Debian Linux — versions 11.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- my.f5.com/manage/s/article/K000149173 (vendor-advisory, Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Issue Tracking, Third Party Advisory)
Frequently asked questions
- What is CVE-2025-23419?
- CVE-2025-23419 is a medium-severity vulnerability in F5 nginx, classified under Incorrect Authorization. CVSS score: 4.3/10. Published 2025-02-05.
- How severe is CVE-2025-23419?
- Medium severity. CVSS v3 base score is 4.3 out of 10.
- Is CVE-2025-23419 known to be exploited?
- 4 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.