HTTP request smuggling in Varnish Cache and Varnish Enterprise



| Updated: 2025-03-25
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2025-30346
CWE-ID CWE-444
Exploitation vector Network
Public exploit N/A
Vulnerable software
 Varnish Enterprise
Server applications / IDS/IPS systems, Firewalls and proxy servers

Varnish Cache
Server applications / IDS/IPS systems, Firewalls and proxy servers

Vendor Varnish Software

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) Inconsistent interpretation of HTTP requests

EUVDB-ID: #VU105850

Risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2025-30346

CWE-ID: CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform HTTP request smuggling attacks.

The vulnerability exists due to improper validation of HTTP/1 client-side desync requests. A remote attacker can send a specially crafted HTTP request to the server and smuggle arbitrary HTTP headers.

Successful exploitation of vulnerability may allow an attacker to poison HTTP cache and perform phishing attacks.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Varnish Enterprise: 6.0.0r0 - 6.0.13r12

Varnish Cache: 7.5.0 - 7.6.1

CPE2.3 External links

https://docs.varnish-software.com/security/VSV00015


Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.



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