CVE-2026-65053: horde imp Cross-site Scripting

Vulnerability summary

CVE-2026-65053 is a medium (CVSS 6.1) Cross-site Scripting vulnerability in horde imp. EPSS estimates a 0.41% chance of exploitation in the next 30 days, higher than 34.2% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 24-08-2026
   PublishedVulnerability first disclosed.
2. 29-08-2026
   Last modifiedVulnerability information updated.

Description

Horde IMP's AppleDouble MIME viewer writes an attacker-controlled attachment name into an HTML status block without escaping it. In lib/Mime/Viewer/Appledouble.php, _IMPrender() obtains the name of the data part with IMP_Contents::getPartName(), which returns the MIME part's own name parameter as supplied by the message, and passes it through sprintf into the text of an IMP_Mime_Status object. IMP_Mime_Status::__toString() concatenates each text entry directly into the surrounding table markup, so the value reaches the rendered page verbatim. A message crafted as multipart/appledouble whose data part carries markup in its name parameter therefore executes script in the context of any user who views it, and the payload persists in the mailbox. Exploitation requires no account on the target system, only the ability to send mail to a user. Version 7.2.0 escapes the value with htmlspecialchars(). The researcher additionally chains this flaw with the arbitrary file read of CVE-2026-58451, and reports that script running in an administrator's session can reach an application code-execution path.

• CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.