Arbitrary file upload in Expressionengine

CVE-2020-13443

ExpressionEngine before 5.3.2 allows remote attackers to upload and execute arbitrary code in a .php%20 file via Compose Msg, Add attachment, and Save As Draft actions. A user with low privileges (member) is able to upload this. It is possible to bypass the MIME type check and file-extension check while uploading new files. Short aliases are not used for an attachment; instead, direct access is allowed to the uploaded files. It is possible to upload PHP only if one has member access, or registration/forum is enabled and one can create a member with the default group id of 5. To exploit this, one must to be able to send and compose messages (at least).

Vulnerability class: Unrestricted File Upload

EPSS: 0.043 (90.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2020-13443?
CVE-2020-13443 is a high-severity vulnerability in Expressionengine, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 8.8/10. Published 2020-06-24.
How severe is CVE-2020-13443?
High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2020-13443 known to be exploited?
4 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.