Description
http-cache-semantics through 4.2.0 contains a cache validation vulnerability in the _varyMatches() function that fails to properly validate Vary header wildcards due to byte-for-byte string comparison. Attackers can request URLs previously fetched by other clients to receive cached responses intended for different users, disclosing sensitive information across clients.
References5
Metrics
- CVSS 3.1
-
5.9
MEDIUM
Score source: NVD
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS 4.0
-
8.2
HIGH
Score source: CNA
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 39 · as of 8 November 2026
- CWE
- CWE-436
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.