How severe is CVE-2020-8866?

CVE-2020-8866 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2020-8866 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-8866?

CVE-2020-8866 primarily affects Horde Groupware. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-8866?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2020-8866 published?

CVE-2020-8866 was published on 2020-03-23 and last updated on 2026-06-17.

CVE-2020-8866

CVE-2020-8866 is a medium-severity vulnerability in Horde Groupware with a CVSS 3.x base score of 6.5. 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-434.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 10% (95th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-434
Affected product: Horde Groupware
Published: 2020-03-23
Last modified: 2026-06-17

Description

This vulnerability allows remote attackers to create arbitrary files on affected installations of Horde Groupware Webmail Edition 5.2.22. Authentication is required to exploit this vulnerability. The specific flaw exists within add.php. The issue results from the lack of proper validation of user-supplied data, which can allow the upload of arbitrary files. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the www-data user. Was ZDI-CAN-10125.

Frequently asked questions

What is CVE-2020-8866?: This vulnerability allows remote attackers to create arbitrary files on affected installations of Horde Groupware Webmail Edition 5.2.22. Authentication is required to exploit this vulnerability. The specific flaw exists within add.php. The issue results from the lack of proper validation of user-supplied data, which can allow the upload of arbitrary files. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the www-data user. Was ZDI-CAN-10125.
How severe is CVE-2020-8866?: CVE-2020-8866 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2020-8866 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-8866?: CVE-2020-8866 primarily affects Horde Groupware. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-8866?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-8866 published?: CVE-2020-8866 was published on 2020-03-23 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:horde:groupware:5.2.22:*:*:*:webmail:*:*:*
cpe:2.3:a:horde:horde_form:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*

More vulnerabilities in Horde Groupware

CVE-2008-7219 — Critical (CVSS 10.0): Horde Kronolith H3 2.1 before 2.1.7 and 2.2 before 2.2-RC2; Nag H3 2.1 before 2.1.4 and 2.2 before 2.2-RC2; Mnemo H3…
CVE-2008-7218 — Critical (CVSS 10.0): Unspecified vulnerability in the Horde API in Horde 3.1 before 3.1.6 and 3.2 before 3.2 before 3.2-RC2; Turba H3 2.1…
CVE-2020-8518 — Critical (CVSS 9.8): Horde Groupware Webmail Edition 5.2.22 allows injection of arbitrary PHP code via CSV data, leading to remote code…
CVE-2013-6364 — High (CVSS 8.8): Horde Groupware Webmail Edition has CSRF and XSS when saving search as a virtual address book
CVE-2019-12095 — High (CVSS 8.8): Horde Trean, as used in Horde Groupware Webmail Edition through 5.2.22 and other products, allows CSRF, as demonstrated…
CVE-2019-9858 — High (CVSS 8.8): Remote code execution was discovered in Horde Groupware Webmail 5.2.22 and 5.2.17. Horde/Form/Type.php contains a…

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