VULNpocalypse

CVE-2026-65053: Horde IMP before 7.2.0 Stored Cross-Site Scripting via AppleDouble Viewer Part Name

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

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.

Description quoted from the CVE record (assigned by VulnCheck, published 2026-08-24).

Weakness: Improper Neutralization of Input During Web Page Generation (‘Cross-site Scripting’)

How it can be exploited

Exploitable over the network with low attack complexity with no special attack requirements needing no privileges and a user must actively take an action. Impact: confidentiality low, integrity low, availability none. 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

CISA assessment (SSVC): CISA assesses that a public proof of concept exists. Automatable: no. Technical impact: partial.

Public exploit evidence (Exploit Observer)

Also known as: EUVD-2026-64899, GHSA-8wpm-p8h2-x7wh

VEDAS cluster: VEDAS:AZULICED

Exploit Observer links 3 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (3)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Research and write-ups (1)

Vulnerability databases and vendor advisories (5)

Catalogue entries, not exploit evidence.

4 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
0.004
low predicted chance of attack
VEDAS
0.978
strong exploit evidence
On CISA KEV
Not listed
Detection rule
Suricata

Who is affected

ProductAffectedNot affected
horde impbefore 7.2.0Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

How to fix it

Fixed versions stated in the CVE record: 7.2.0.

Vendor guidance:

How to detect it

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2026-65053 Horde IMP AppleDouble MIME Name Stored XSS (crafted email). Add them to your Suricata rule set and reload.

Show the rules
suricata
# CVE-2026-65053 - Horde IMP AppleDouble MIME viewer (lib/Mime/Viewer/Appledouble.php) writes
# the data part's name parameter into an HTML status block without escaping, so a
# multipart/appledouble message whose data part carries markup in its name parameter yields
# stored XSS when any user views the message. The attack vector is a crafted email, so detect
# the malicious MIME shape (multipart/appledouble with an XSS payload in the name parameter)
# in the SMTP stream.
alert smtp $EXTERNAL_NET any -> $HOME_NET any (msg:"VEDAS CVE-2026-65053 Horde IMP AppleDouble MIME Name Stored XSS (crafted email)"; flow:established,to_server; file.data; content:"multipart/appledouble"; nocase; fast_pattern; content:"name"; nocase; distance:0; pcre:"/name\s*=\s*\x22?[^\x22\r\n]{0,200}(?:<|%3c)\s*(?:script|svg|img|iframe|body|details|a\b|on[a-z]+\s*=)/i"; classtype:web-application-attack; reference:cve,CVE-2026-65053; reference:url,https://www.exploit.observer/?keyword=CVE-2026-65053&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=horde&match=exact; sid:1099005; rev:1;)

CVE-2026-65053.rules on GitHub

References

Vendor advisories and patches

Exploits and technical analysis

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.