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🛡️ CVE-2026-40701 — dos

🟡 CVSS 5.0 — Medium ✅ No Known Exploit CWE-416 NVD
5.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

NGINX ngx_http_ssl_module vulnerability

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 this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity none, availability low.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: None.
  • Availability impact: Low — limited, and the attacker does not choose what is affected.

Weakness class

CVE-2026-40701 is classified as CWE-416: Use After Free. Memory is used after being released, so its contents may already belong to something else.

Affected software

CVE-2026-40701 is recorded against 9 packages.

  • dos
  • nginx
  • nginx-gateway
  • nginx-gateway-fabric (from 2.0.0 up to 2.6.0)
  • nginx-ingress-controller (from 5.0.0 up to 5.4.2)
  • nginx-instance-manager (from 2.16.0 up to 2.22.0)
  • nginx-open-source (from 1.19.0 up to 1.30.0)
  • nginx-plus (from r32 up to r36)
  • waf (from 5.9.0 up to 5.12.1)

Timeline and source

Published on 13 May 2026 and last revised on 23 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

my.f5.com

Other advisories for this package

dos has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-416: Use After Free) in other software:

CVE-2026-40701 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity MEDIUM
CVSS Score 5.0
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
CWE CWE-416
Public Exploit ✅ No
Source NVD
Published 2026-05-13
Updated 2026-08-20
Modified 2026-06-23
Fix URL N/A

Affected Packages

Software From version Fixed in
dos — —
nginx — —
nginx-gateway — —
nginx-gateway-fabric 2.0.0 2.6.0
nginx-ingress-controller 5.0.0 5.4.2
nginx-instance-manager 2.16.0 2.22.0
nginx-open-source 1.19.0 1.30.0
nginx-plus r32 r36
waf 5.9.0 5.12.1

References

Mitigation, Vendor Advisory https://my.f5.com/manage/s/article/K000161021

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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