How severe is CVE-2016-9920?

CVE-2016-9920 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2016-9920 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-9920?

CVE-2016-9920 primarily affects Roundcube Webmail. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-9920?

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-2016-9920 published?

CVE-2016-9920 was published on 2016-12-08 and last updated on 2026-06-17.

CVE-2016-9920

CVE-2016-9920 is a high-severity vulnerability in Roundcube Webmail with a CVSS 3.x base score of 7.5. 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-284.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 6.0
EPSS exploit prediction: 6% (92nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-284
Affected product: Roundcube Webmail
Published: 2016-12-08
Last modified: 2026-06-17

Description

steps/mail/sendmail.inc in Roundcube before 1.1.7 and 1.2.x before 1.2.3, when no SMTP server is configured and the sendmail program is enabled, does not properly restrict the use of custom envelope-from addresses on the sendmail command line, which allows remote authenticated users to execute arbitrary code via a modified HTTP request that sends a crafted e-mail message.

Frequently asked questions

What is CVE-2016-9920?: steps/mail/sendmail.inc in Roundcube before 1.1.7 and 1.2.x before 1.2.3, when no SMTP server is configured and the sendmail program is enabled, does not properly restrict the use of custom envelope-from addresses on the sendmail command line, which allows remote authenticated users to execute arbitrary code via a modified HTTP request that sends a crafted e-mail message.
How severe is CVE-2016-9920?: CVE-2016-9920 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2016-9920 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-9920?: CVE-2016-9920 primarily affects Roundcube Webmail. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-9920?: 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-2016-9920 published?: CVE-2016-9920 was published on 2016-12-08 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*
cpe:2.3:a:roundcube:webmail:1.2.0:*:*:*:*:*:*:*
cpe:2.3:a:roundcube:webmail:1.2.1:*:*:*:*:*:*:*
cpe:2.3:a:roundcube:webmail:1.2.2:*:*:*:*:*:*:*

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