SB20260917230 - Remote denial of service in Varnish Cache

Description

This security bulletin contains information about 1 vulnerability.

1) Buffer overflow (CVE-ID: N/A)

CWE-ID: CWE-120 - Buffer overflow

CVSSv4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to a workspace buffer overflow in the .upper() and .lower() VCL string type methods when processing a crafted request containing a string that exhausts the remaining workspace. A remote attacker can send a specially crafted request to cause a denial of service.

Exploitation requires prior knowledge of the VCL in use and a string that fills the remaining workspace while staying within request size limits.

Remediation

Install update from vendor's website.

References

• https://docs.varnish-software.com/security/VSV00020
• https://vinyl-cache.org/security/VSV00020.html