CVE-2026-126813 (CVSS 6.8)

Description

Roundcube Webmail before 1.6.21 and 1.7.x before 1.7.6 contains an IMAP command injection vulnerability that allows attackers to inject commands via CRLF in the _uid parameter when messages_cache is enabled. Attackers can lure logged-in victims into opening crafted GET links to mail/show or mail/get, executing IMAP commands that delete messages, change flags, or grant mailbox access via SETACL.

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CVSS v3.1 Score

6.8

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0106

Probability of exploitation

0.65%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-93 CWE-93

References

Other References

https://github.com/roundcube/roundcubemail/blob/1.7.5/program/lib/Roundcube/rcube_imap_generic.php#L2892 https://github.com/roundcube/roundcubemail/commit/2ea63692178cab5cea486c7c630901b7f6852c80 https://github.com/roundcube/roundcubemail/commit/4cb1cf106b9ca5d465ed4924f2fab5d5108edfeb https://github.com/roundcube/roundcubemail/commit/d1dda13597ceed9df49d434a8d88b758bcf6ef5c https://github.com/roundcube/roundcubemail/releases/tag/1.6.21 https://github.com/roundcube/roundcubemail/releases/tag/1.7.6 https://roundcube.net/news/2026/11/09/security-updates-1.6.21-and-1.7.6 https://www.vulncheck.com/advisories/roundcube-webmail-before-1.6.21-and-1.7.6-imap-command-injection-via-uid

Frequently Asked Questions

What is CVE-2026-126813? +

Roundcube Webmail before 1.6.21 and 1.7.x before 1.7.6 contains an IMAP command injection vulnerability that allows attackers to inject commands via CRLF in the _uid parameter when messages_cache is enabled. Attackers can lure logged-in victims into opening crafted GET links to mail/show or mail/get, executing IMAP commands that delete messages, change flags, or grant mailbox access via SETACL. It has a CVSS v3.1 base score of 6.8 (MEDIUM).

How severe is CVE-2026-126813? +

CVE-2026-126813 has a CVSS v3.1 score of 6.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0106, placing it in the 1th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-126813? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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