Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Caddy's caddyhttp module, versions 2.7.5 up to but not including 2.11.2, has a flaw in the vars_regexp matcher where user-supplied request header values are expanded a second time for placeholders. A remote attacker able to send requests to a server with a vars_regexp configuration that matches such input could read environment variables, file contents up to 1MB, and system information. Upgrade to version 2.11.2, which fixes the issue.
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 |
|---|---|---|---|---|
| 5.5 | Medium | 4.0 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0047, the 40th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 15:09 UTC First seen by agentprime
- 31 Oct 2026, 15:09 UTC Confirmed by OSV