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3.9 KiB
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3.9 KiB
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{"schema_version":"1.9.0","id":"GHSA-879p-475x-rqh2","published":"2026-02-24T20:37:35Z","modified":"2026-02-27T19:54:36Z","aliases":["CVE-2026-27589","GO-2026-4537"],"summary":"Caddy is vulnerable to cross-origin config application via local admin API /load ","details":"commit: e0f8d9b2047af417d8faf354b675941f3dac9891 (as-of 2026-02-04)\nchannel: GitHub security advisory (per SECURITY.md)\n\n## summary\n\nThe local caddy admin API (default listen `127.0.0.1:2019`) exposes a state-changing `POST /load` endpoint that replaces the entire running configuration.\n\nWhen origin enforcement is not enabled (`enforce_origin` not configured), the admin endpoint accepts cross-origin requests (e.g., from attacker-controlled web content in a victim browser) and applies an attacker-supplied JSON config. this can change the admin listener settings and alter HTTP server behavior without user intent.\n\n## Severity\n\nMedium\n\nJustification:\n- The attacker can apply an arbitrary caddy config (integrity impact) by driving a victim’s local admin API.\n- Exploitation requires a victim running caddy with the admin API enabled and visiting an attacker-controlled page (or otherwise issuing the request from an untrusted local client).\n\n## Affected component\n\n- `caddyconfig/load.go: adminLoad.handleLoad` (`/load` admin endpoint)\n- Pinned callsite: https://github.com/caddyserver/caddy/blob/e0f8d9b2047af417d8faf354b675941f3dac9891/caddyconfig/load.go#L73\n\n## Reproduction\n\nAttachment: `poc.zip` (integration harness) with canonical and control runs.\n\n```bash\nunzip -q -o poc.zip -d poc\ncd poc/poc-F-CADDY-ADMIN-LOAD-001\nmake test\n```\n\nExpected output (excerpt):\n\n```\n[CALLSITE_HIT]: adminLoad.handleLoad\n[PROOF_MARKER]: http_code=200 admin_moved=true response_pwned=true\n```\n\nControl output (excerpt):\n\n```\n[NC_MARKER]: http_code=403 load_blocked=true admin_moved=false response_pwned=false\n```\n\n## Impact\n\nAn attacker can replace the running caddy configuration via the local admin API. Depending on the deployed configuration/modules, this can:\n- Change admin listener settings (e.g., move the admin listener to a new address)\n- Change HTTP server behavior (e.g., alter routes/responses)\n\n## Suggested remediation\n\nEnsure cross-origin web content cannot trigger `POST /load` on the local admin API by default, for example by:\n- Enabling origin enforcement by default for unsafe methods, and/or\n- Requiring an unguessable token for `/load` (and other state-changing admin endpoints).\n\n[poc.zip](https://github.com/user-attachments/files/25079818/poc.zip)\n[PR_DESCRIPTION.md](https://github.com/user-attachments/files/25079820/PR_DESCRIPTION.md)","affected":[{"package":{"name":"github.com/caddyserver/caddy/v2","ecosystem":"Go","purl":"pkg:golang/github.com/caddyserver/caddy/v2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.11.1"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-879p-475x-rqh2/GHSA-879p-475x-rqh2.json"}}],"references":[{"type":"WEB","url":"https://github.com/caddyserver/caddy/security/advisories/GHSA-879p-475x-rqh2"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27589"},{"type":"WEB","url":"https://github.com/caddyserver/caddy/commit/65e0ddc22137bbbaa68c842ae0b98d0548504545"},{"type":"PACKAGE","url":"https://github.com/caddyserver/caddy"},{"type":"WEB","url":"https://github.com/caddyserver/caddy/releases/tag/v2.11.1"},{"type":"WEB","url":"https://github.com/user-attachments/files/25079818/poc.zip"},{"type":"WEB","url":"https://github.com/user-attachments/files/25079820/PR_DESCRIPTION.md"},{"type":"WEB","url":"https://pkg.go.dev/vuln/GO-2026-4537"}],"database_specific":{"cwe_ids":["CWE-352"],"github_reviewed":true,"github_reviewed_at":"2026-02-24T20:37:35Z","nvd_published_at":"2026-02-24T17:29:04Z","severity":"MODERATE"},"severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P"}]} |