CVE-2026-40521 FrontAccounting < 2.4.20 Path Traversal RCE via attachment upload
Authenticated attackers can achieve remote code execution by uploading malicious files via path traversal in the attachment handler.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-40521?
CVE-2026-40521 is a high-severity path traversal vulnerability in FrontAccounting, published on 29 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
FrontAccounting before 2.4.20 contains a path traversal vulnerability in the attachment upload handler that allows authenticated attackers to execute arbitrary code by uploading files with traversal sequences in the unique_name parameter. Attackers can supply path traversal sequences ../../../shell.php to write files outside the intended attachments directory into the web root, and by uploading PHP files without extension validation, achieve remote code execution as the web server user.
Weakness: CWE-22
Which versions are affected by CVE-2026-40521?
How do I fix CVE-2026-40521?
No fix has been published for CVE-2026-40521 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-40521 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40521 exists.
Sources
Also known as GHSA-9fmm-h59x-wr53.