CVE-2026-34475: Critical severity Varnish Software Varnish Cache vulnerability

Published Mar 27, 2026
·
Updated

Varnish Cache before 8.0.1 and Varnish Enterprise before 6.0.16r12, in certain unchecked req.url scenarios, mishandle URLs with a path of / for HTTP/1.1, potentially leading to cache poisoning or authentication bypass.

Affected Software

15 affected components
Varnish Software Varnish Cache<8.0.1
Varnish Software Varnish Enterprise<6.0.16r12
Varnish-software Varnish Enterprise<=6.0.15
Varnish-software Varnish Enterprise=6.0.16-r1
Varnish-software Varnish Enterprise=6.0.16-r10
Varnish-software Varnish Enterprise=6.0.16-r11
Varnish-software Varnish Enterprise=6.0.16-r2
Varnish-software Varnish Enterprise=6.0.16-r3
Varnish-software Varnish Enterprise=6.0.16-r4
Varnish-software Varnish Enterprise=6.0.16-r5
Varnish-software Varnish Enterprise=6.0.16-r6
Varnish-software Varnish Enterprise=6.0.16-r7
Varnish-software Varnish Enterprise=6.0.16-r8
Varnish-software Varnish Enterprise=6.0.16-r9
Vinyl-cache Vinyl Cache<8.0.1

Event History

Mar 27, 2026
CVE Published
via MITRE·07:40 PM
Data Sourced
via MITRE·07:40 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·08:16 PM
DescriptionSeverityWeaknessAffected Software
Free Weekly Intel

Don't miss critical vulnerabilities

Join thousands of security professionals who receive our weekly digest of trending CVEs, zero-days, and exploited vulnerabilities.

No spam. Unsubscribe anytime.

Frequently Asked Questions

1

What is the severity of CVE-2026-34475?

CVE-2026-34475 has a high severity rating due to its potential to lead to cache poisoning and authentication bypass.

2

How do I fix CVE-2026-34475?

The recommended fix for CVE-2026-34475 is to update Varnish Cache to version 8.0.1 or later, or Varnish Enterprise to version 6.0.16r12 or later.

3

What vulnerabilities are associated with CVE-2026-34475?

CVE-2026-34475 is associated with cache poisoning and authentication bypass vulnerabilities due to improper handling of certain URLs.

4

What versions of Varnish are affected by CVE-2026-34475?

CVE-2026-34475 affects Varnish Cache versions before 8.0.1 and Varnish Enterprise versions before 6.0.16r12.

5

How does CVE-2026-34475 impact web security?

CVE-2026-34475 can significantly compromise web security by allowing attackers to manipulate cache responses and bypass authentication mechanisms.

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203