CVE-2026-93894
CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/AU:N/R:A/V:D/RE:L/U:Clear
Summary
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 (http_req_size, http_req_hdr_len, etc.).
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Vinyl-Cache | Vinyl Cache | 0 < 9.0.2 | affected |
| Vinyl-Cache | Vinyl Cache | 0 < 90f5bacc14b2404e6cc349ba015f0f73b8515136 | affected |
| Varnish-Software | Varnish Cache | 9.0.0 < 9.0.4 | affected |
| Varnish-Software | Varnish Cache | 0 < c5078ae575201b05ae8674a90ddb19ffe7f4b439 | affected |
| Varnish-Software | Varnish Cache | 6.3.0 <= 8.0.2 | affected |
Weaknesses
- CWE-787: CWE-787 Out-of-bounds Write
Workarounds
replace the .upper() and .lower() VCL type method calls by their respective vmod_std counterparts: std.toupper() and std.tolower().
References
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