ngx_cache_purge before 3.0.4 can allow file deletion via a symlink attack in certain situations where nginx and a served application (e.g., WordPress) run under the same user account. The attacker must be able to create a symlink inside the cache path. Version 3.0.4 fixes this for the case of a symlink created at an arbitrary earlier time, but does not resolve an applicable TOCTOU race condition. (The ngx_cache_purge module follows symlinks while walking the cache directory tree during purge operations. The module relies on nginx's ngx_walk_tree(), which relies on stat() and therefore follows symlinks.)
Advisories

No advisories yet.

Fixes

Solution

Fixed in commit a6da135 (PR #72) on the releases/stable-3.0 branch. 2.4 through 2.5.6 users should upgrade to 3.x, or backport the change to the two ngx_walk_tree() call sites in those versions.


Workaround

Restrict write access to the cache directories and all of their parent directories to the nginx user only, and do not run nginx and untrusted application code (for example PHP-FPM) as the same user. Remove any symbolic links found inside configured cache paths (find <cache_path> -type l). These measures also limit the similar traversal in nginx's own cache loader, which the fix in the module does not change.

History

Mon, 12 Oct 2026 04:45:00 +0000

Type Values Removed Values Added
Title Symlink‑Based File Deletion via ngx_cache_purge

Mon, 12 Oct 2026 03:00:00 +0000

Type Values Removed Values Added
Description ngx_cache_purge before 3.0.4 can allow file deletion via a symlink attack in certain situations where nginx and a served application (e.g., WordPress) run under the same user account. The attacker must be able to create a symlink inside the cache path. Version 3.0.4 fixes this for the case of a symlink created at an arbitrary earlier time, but does not resolve an applicable TOCTOU race condition. (The ngx_cache_purge module follows symlinks while walking the cache directory tree during purge operations. The module relies on nginx's ngx_walk_tree(), which relies on stat() and therefore follows symlinks.)
Weaknesses CWE-61
References
Metrics cvssV3_1

{'score': 3.6, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published:

Updated: 2026-10-12T02:27:15.378Z

Reserved: 2026-10-12T02:27:14.593Z

Link: CVE-2026-108981

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-12T03:17:18.503

Modified: 2026-10-12T03:17:18.503

Link: CVE-2026-108981

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-12T04:30:06Z

Weaknesses