Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Caddy's reverse proxy, in the github.com/caddyserver/caddy/v2 Go module before 2.11.5, does not strip hop-by-hop headers (such as Alt-Svc, Keep-Alive, Proxy-Authenticate, Transfer-Encoding, and Trailer) from upstream responses to WebSocket upgrade requests. An attacker who controls or compromises an upstream server could make these headers reach clients, such as Set-Cookie for cookie injection or Alt-Svc for connection hijacking. Upgrade to version 2.11.5 or later, which contains the fix.
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 |
|---|---|---|---|---|
| 2.9 | Low | 4.0 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS No score.
Timeline
- 31 Oct 2026, 14:11 UTC First seen by agentprime
- 31 Oct 2026, 14:11 UTC Confirmed by OSV
- 5 Nov 2026, 20:15 UTC Confirmed by the CVE List
- 5 Nov 2026, 21:18 UTC Confirmed by NVD