What is the CVSS score of EUVD-2026-16801?

EUVD-2026-16801 has a CVSS 3.1 base score of 5.4 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of Varnish Enterprise are affected by EUVD-2026-16801?

CVE-2026-34475 presents moderate security risk rated CVSS 5.4. Exploitation could compromise the security of affected deployments.. A patch is available.

How to fix or mitigate EUVD-2026-16801?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Monitor vendor channels for patch availability.

Varnish Enterprise EUVD-2026-16801

| CVE-2026-34475 MEDIUM

Incorrect Behavior Order: Validate Before Canonicalize (CWE-180)

2026-03-27 cve@mitre.org

Authentication Bypass Varnish Enterprise Vinyl Cache

5.4

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

5.4 MEDIUM

AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N

SUSE

MEDIUM

qualitative

Red Hat

5.4 MEDIUM

qualitative

Primary rating from NVD.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Patch available

Apr 16, 2026 - 05:29 EUVD

8.0.1,6.0.17

EUVD ID Assigned

Mar 27, 2026 - 20:22 euvd

EUVD-2026-16801

Analysis Generated

Mar 27, 2026 - 20:22 vuln.today

CVE Published

Mar 27, 2026 - 20:16 nvd

MEDIUM 5.4

DescriptionCVE.org

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.

AnalysisAI

Varnish Cache before 8.0.1 and Varnish Enterprise before 6.0.16r12 mishandle HTTP/1.1 URLs with a root path (/) in unchecked req.url scenarios, enabling cache poisoning and authentication bypass attacks. Unauthenticated remote attackers can exploit this with moderate complexity to poison cached content or bypass authentication controls affecting downstream clients. No active exploitation has been confirmed, though the vulnerability carries a 5.4 CVSS score reflecting network accessibility and partial impact to confidentiality and integrity.

Technical ContextAI

Varnish Cache is an HTTP accelerator and reverse proxy that caches web content to improve performance. The vulnerability stems from improper URL handling in HTTP/1.1 request processing, specifically when the path component is set to the root path (/). CWE-180 (Incorrect Behavior of Shift and Rotation Operator) typically involves bitwise operation errors, but in this context likely indicates unsafe transformation or normalization of URL path components. When req.url is not properly validated before use in caching decisions or authentication checks, attackers can craft malicious requests with root paths that bypass security controls. The affected versions are Varnish Cache before 8.0.1 (CPE: cpe:2.3:a:varnish:varnish_cache:*:*:*:*:*:*:*:*) and Varnish Enterprise before 6.0.16r12 (CPE: cpe:2.3:a:varnish:varnish_enterprise:*:*:*:*:*:*:*:*).

RemediationAI

Upgrade Varnish Cache to version 8.0.1 or later, which includes the fix for improper HTTP/1.1 URL path handling. Varnish Enterprise users should update to 6.0.16r12 or later. For users unable to immediately patch, review and strengthen validation of req.url in Varnish Configuration Language (VCL) policies, ensuring that root path requests (/) are explicitly handled and do not bypass intended caching or authentication logic. Disable or restrict caching of authentication-sensitive responses until patched. Consult the official advisory at https://vinyl-cache.org/security/VSV00018.html for detailed configuration workarounds and patch deployment instructions.