CVE-2026-74997Network attack vectorHinoki check available

Authenticated command execution via repeated placeholder expansion

Published Aug 17, 2026 · Updated Aug 17, 2026

OS command injection in Roundcube Webmail lets remote authenticated users execute commands via crafted cmd_learn placeholders. In plugins/markasjunk/drivers/cmd_learn.php, the driver builds a shell command with sequential str_replace calls, so placeholder tokens embedded in already escaped values are expanded again after escaping. Reachability requires a logged-in session and a deployment that enables the markasjunk plugin with the cmd_learn driver; successful exploitation runs code as the web server account.

CVSS severity8.8
High
EPSS probability0.78%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

OS command injection in Roundcube Webmail lets remote authenticated users execute commands via crafted cmd_learn placeholders. In plugins/markasjunk/drivers/cmd_learn.php, the driver builds a shell command with sequential str_replace calls, so placeholder tokens embedded in already escaped values are expanded again after escaping. Reachability requires a logged-in session and a deployment that enables the markasjunk plugin with the cmd_learn driver; successful exploitation runs code as the web server account.

The record

CVE
CVE-2026-74997
Published
Aug 17, 2026
Updated
Aug 17, 2026
Vendor
Roundcube
Product
Roundcube Webmail
Classifications
CWE-78, T1059.004
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

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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

8.8MITRECVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059.004Unix Shell

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

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Your stack

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