medium6.5
CVE-2026-77281
Caddy: rewrite placeholder re-expansion, unbounded body buffer DoS, and fileHidden case-sensitivity bypass
Impact
Caddy is an extensible server platform that uses TLS by default. In version 2.11.3 and earlier, three configuration-dependent weaknesses affect the handler and placeholder layer. In modules/caddyhttp/rewrite/rewrite.go, Rewrite.Rewrite() can pass attacker-controlled replacement bytes through buildQueryString for a second placeholder expansion when a rewrite URI ends with a literal question mark, allowing injected environment or request-variable placeholders to disclose data and, when the file provider is registered, allowing injected file placeholders to disclose readable files. The issue is fixed in version 2.11.4.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/caddyserver/caddy/v2 | <= 2.11.3 | 2.11.4 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-j8px-rmrx-76h9
- https://github.com/caddyserver/caddy/security/advisories/GHSA-j8px-rmrx-76h9
- https://nvd.nist.gov/vuln/detail/CVE-2026-77281
- https://github.com/caddyserver/caddy/pull/7761
- https://github.com/caddyserver/caddy/commit/176b043b0104cee3f894023cd5a598ac29e404bb
- https://github.com/caddyserver/caddy/releases/tag/v2.11.4