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.
Published: 2026-08-24
Score: 5.1 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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Advisories

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History

Mon, 24 Aug 2026 15:00:00 +0000

Type Values Removed Values Added
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.
Title Horde IMP before 7.2.0 Stored Cross-Site Scripting via AppleDouble Viewer Part Name
First Time appeared Horde
Horde horde Imp
Weaknesses CWE-79
CPEs cpe:2.3:a:horde:horde_imp:*:*:*:*:*:*:*:*
Vendors & Products Horde
Horde horde Imp
References
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}

cvssV4_0

{'score': 5.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-08-24T14:53:43.219Z

Reserved: 2026-07-21T14:05:53.719Z

Link: CVE-2026-65053

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-24T15:16:39.380

Modified: 2026-08-24T15:16:39.380

Link: CVE-2026-65053

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses
  • CWE-79

    Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')