How severe is CVE-2016-5303?

CVE-2016-5303 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2016-5303 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (71st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-5303?

CVE-2016-5303 primarily affects Horde Groupware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-5303?

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

When was CVE-2016-5303 published?

CVE-2016-5303 was published on 2016-12-20 and last updated on 2026-06-17.

CVE-2016-5303

CVE-2016-5303 is a medium-severity vulnerability in Horde Groupware with a CVSS 3.x base score of 6.1. 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-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 2% (71st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Horde Groupware
Published: 2016-12-20
Last modified: 2026-06-17

Description

Cross-site scripting (XSS) vulnerability in the Horde Text Filter API in Horde Groupware and Horde Groupware Webmail Edition before 5.2.16 allows remote attackers to inject arbitrary web script or HTML via crafted data:text/html content in a form (1) action or (2) xlink attribute.

Frequently asked questions

What is CVE-2016-5303?: Cross-site scripting (XSS) vulnerability in the Horde Text Filter API in Horde Groupware and Horde Groupware Webmail Edition before 5.2.16 allows remote attackers to inject arbitrary web script or HTML via crafted data:text/html content in a form (1) action or (2) xlink attribute.
How severe is CVE-2016-5303?: CVE-2016-5303 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2016-5303 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-5303?: CVE-2016-5303 primarily affects Horde Groupware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-5303?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2016-5303 published?: CVE-2016-5303 was published on 2016-12-20 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:horde:groupware:5.2.15:*:*:*:*:*:*:*
cpe:2.3:a:horde:groupware:5.2.15:*:*:*:webmail:*:*:*

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