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Fencer Vulns
medium 5.4

CVE-2026-34475 json

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 /…

published 2026-03-27 7 mo ago modified 2026-10-26 13 d ago also EUVD-2026-16801

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 11%
public exploits
0
none known

Summary

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.

Patch / fix

  • varnish-software Varnish Cache 6.0.17 LTS, 8.0.1
  • varnish Debian 13 7.7.0-3+deb13u2

debian advisories DEBIAN-CVE-2026-34475

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-34475 updated cvss 5.4

Varnish Cache: Varnish Cache and Varnish Enterprise: Cache poisoning and authentication bypass via unchecked URL handling

  • Red Hat Enterprise Linux 8 varnish, varnish-modules Red Hat Enterprise Linux 9 varnish-modules Red Hat Enterprise Linux 10 varnish, varnish-modules
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 8 redhat-user-workloads/osci-rhel-containers-tenant/varnish-6-8-10/varnish-6-8-10 Red Hat Enterprise Linux 9 varnish, redhat-user-workloads/osci-rhel-containers-tenant/rhel-9-6/varnish-6-9-6/varnish-6-9-6, redhat-user-workloads/osci-rhel-containers-tenant/rhel-9-7/varnish-6-9-7/varnish-6-9-7 Red Hat Enterprise Linux 10 redhat-user-workloads/osci-rhel-containers-tenant/rhel-10-0/varnish-7-10-0/varnish-7-10-0, redhat-user-workloads/osci-rhel-containers-tenant/rhel-10-1/varnish-7-10-1/varnish-7-10-1
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
7 mo ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • varnish-software Varnish Cache

Classification

Weakness
  • CWE-180 Incorrect Behavior Order: Validate Before Canonicalize

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.