CVE-2026-93894: Buffer Overflow
In Vinyl Cache before 9.0,2, workspace buffer overflow vulnerability was found in the .upper() and .lower() string type methods of VCL. This can be used as a remote denial of service (DoS) vector to make the child process segfault or assert, and then restart. Effectively exploiting this vulnerability requires prior knowledge about the VCL in use and the ability to craft a request that contains a string that is long enough to fill the remaining workspace at the call site while staying under the different request size limits (httpreqsize, httpreqhdrlen, etc.).
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Vinyl Cacheto a version that resolves this vulnerability.Fixed in 9.0,2
Event History
Frequently Asked Questions
What does an attacker need to exploit this issue?
The attacker needs prior knowledge of the VCL in use and must be able to craft a request containing a string large enough to exhaust the remaining workspace at the relevant .upper() or .lower() call site. The request must also remain within configured request-size limits such as http_req_size and http_req_hdr_len.
Who is exposed to remote denial of service?
Deployments using affected Vinyl Cache versions with VCL that invokes the .upper() or .lower() string methods may be exposed if remote clients can submit suitably crafted requests. Successful exploitation can cause a child process to segfault or assert and then restart.
How can I determine whether my configuration is susceptible?
Review the deployed VCL for uses of the .upper() and .lower() string methods, then assess the available workspace at each call site and the applicable request-size limits. Susceptibility depends on whether an attacker can supply a string that fills the remaining workspace without exceeding those limits.