Is CVE-2016-5303 in the CISA KEV catalog?

No. CVE-2016-5303 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2016-5303?

CVE-2016-5303 has a CVSS v3 base score of 6.1 (MEDIUM).

What is the EPSS score for CVE-2016-5303?

CVE-2016-5303 has an EPSS score of 1.51% (71th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2016-5303?

Upgrade php-horde-text-filter on debian 11 to 2.3.5-1 or later.

CVE & CISA-KEV Catalog

CVE-2016-5303

MEDIUMEPSS 71th pctl

6.1

CVSS v3

NVD

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.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

php-horde-text-filterDebian

Fixed in:2.3.5-1CVE-2016-5303

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Exploit Intelligence

1.51%probability of exploitation in 30 days

71stpercentile

Elevated risk: more likely to be exploited than 71% of all known CVEs.

References

Patch2

Third-Party Advisory2

Other references1

securityfocus.com

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-06.