CVE-2026-65053 Horde IMP before 7.2.0 Stored Cross-Site Scripting via AppleDouble Viewer Part Name
Attackers can execute arbitrary scripts in victim browsers via crafted email attachments, potentially leading to account takeover or code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-65053?
CVE-2026-65053 is a medium-severity cross-site scripting vulnerability in horde imp, published on 24 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-65053?
How do I fix CVE-2026-65053?
No fix has been published for CVE-2026-65053 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-65053 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-65053 exists.
Sources
Also known as DEBIAN-CVE-2026-65053, GHSA-8wpm-p8h2-x7wh, UBUNTU-CVE-2026-65053.