Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
The http4k-core library is vulnerable in versions from 6.0.0.0 up to 6.48.0.0, from 5.0.0.0 up to 5.42.0.0, and below 4.51.0.0. The old BasicCookieStorage class did not enforce RFC 6265 domain, path, and Secure rules, so a client using one instance across multiple origins or schemes could leak cookies between them or send Secure cookies over plain HTTP. Upgrade to 6.48.0.0, 5.42.0.0, or 4.51.0.0; the fix adds DefaultCookieStorage as the default, and the old class is renamed InsecureCookieStorage. Single-origin use is not affected.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 8.3 | High | 4.0 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N | CNA (VulnCheck) |
- CISA KEV Not listed.
- EPSS 0.0024, the 15th percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:16 UTC First seen by agentprime
- 31 Oct 2026, 14:16 UTC Confirmed by OSV