How severe is CVE-2018-9846?

CVE-2018-9846 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2018-9846 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-9846?

CVE-2018-9846 primarily affects Roundcube Webmail. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-9846?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2018-9846 published?

CVE-2018-9846 was published on 2018-04-07 and last updated on 2026-06-17.

CVE-2018-9846

CVE-2018-9846 is a high-severity vulnerability in Roundcube Webmail with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.8
EPSS exploit prediction: 2% (82nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Roundcube Webmail
Published: 2018-04-07
Last modified: 2026-06-17

Description

In Roundcube from versions 1.2.0 to 1.3.5, with the archive plugin enabled and configured, it's possible to exploit the unsanitized, user-controlled "_uid" parameter (in an archive.php _task=mail&_mbox=INBOX&_action=plugin.move2archive request) to perform an MX (IMAP) injection attack by placing an IMAP command after a %0d%0a sequence. NOTE: this is less easily exploitable in 1.3.4 and later because of a Same Origin Policy protection mechanism.

Frequently asked questions

What is CVE-2018-9846?: In Roundcube from versions 1.2.0 to 1.3.5, with the archive plugin enabled and configured, it's possible to exploit the unsanitized, user-controlled "_uid" parameter (in an archive.php _task=mail&_mbox=INBOX&_action=plugin.move2archive request) to perform an MX (IMAP) injection attack by placing an IMAP command after a %0d%0a sequence. NOTE: this is less easily exploitable in 1.3.4 and later because of a Same Origin Policy protection mechanism.
How severe is CVE-2018-9846?: CVE-2018-9846 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2018-9846 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-9846?: CVE-2018-9846 primarily affects Roundcube Webmail. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-9846?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-9846 published?: CVE-2018-9846 was published on 2018-04-07 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

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