CVE-2026-74999Network attack vectorHinoki check available

Stored XSS via unescaped addcontact error

Published Aug 17, 2026 · Updated Aug 17, 2026

Stored XSS in Add to address book in Roundcube Webmail 1.6.0 through 1.6.17 and 1.7.0 through 1.7.2 lets remote authenticated users run script. In program/actions/mail/addcontact.php, the action passes an attacker-controlled $error string to output->show_message() without escaping; the fix wraps that value in rcmail::Q() before rendering. Exploitation requires low-privileged access and a user to reach the affected workflow, and the practical consequence is script execution in the victim webmail session with low confidentiality and integrity impact.

CVSS severity5.4
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stored XSS in Add to address book in Roundcube Webmail 1.6.0 through 1.6.17 and 1.7.0 through 1.7.2 lets remote authenticated users run script. In program/actions/mail/addcontact.php, the action passes an attacker-controlled $error string to output->show_message() without escaping; the fix wraps that value in rcmail::Q() before rendering. Exploitation requires low-privileged access and a user to reach the affected workflow, and the practical consequence is script execution in the victim webmail session with low confidentiality and integrity impact.

The record

CVE
CVE-2026-74999
Published
Aug 17, 2026
Updated
Aug 17, 2026
Vendor
Roundcube
Product
Roundcube Webmail
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.6.0 <1.6.18
  2. Affected versionversion=1.7.0 <1.7.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Roundcube · Roundcube Webmailversion=1.6.0 <1.6.18; version=1.7.0 <1.7.3

Published CVSS scores

5.4MITRECVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo