CVE-2026-40521
CWE-22Published: June 29, 2026· Updated: Jun 30, 2026
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.
Technical Analysis
CVE-2026-40521 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.8.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
All References (4)
Quick Facts
Related CVEs (CWE-22)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-40521 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts