CVE-2020-18449: Cross Site Scripting (XSS) vulnerability exists in UKCMS v1.1.10 via data in the index function in Single.php

Routine

MEDIUM 5.4DOWNGRADE

CVE-2020-18449 is a medium-severity flaw (CVSS 5.4) affecting ukcms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cross Site Scripting (XSS) vulnerability exists in UKCMS v1.1.10 via data in the index function in Single.php

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.5% (top 56%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-08-12
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: ukcms

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-08-12 18:15 UTCPublished CVE record published
2026-06-17 02:59 UTCUpdated Record last modified

ukcms ukcms DOWNGRADE

Affected: 1.1.10

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.1.10

1. Check installed version

apt-cache policy ukcms || rpm -q ukcms || ukcms --version

2. No fixed release: DOWNGRADE to a release before 1.1.10 (Debian / Ubuntu)

apt-cache madison ukcms sudo apt install ukcms=<VERSION_BEFORE_1.1.10> sudo apt-mark hold ukcms

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list ukcms sudo dnf downgrade ukcms-<VERSION_BEFORE_1.1.10> sudo dnf versionlock add ukcms

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-18449?

ukcms: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-18449 being exploited?

CVE-2020-18449 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-18449 affect?

CVE-2020-18449 affects ukcms. Severity is medium (CVSS 5.4). Cross Site Scripting (XSS) vulnerability exists in UKCMS v1.1.10 via data in the index function in Single.php

How urgent is CVE-2020-18449?

Priority 35/100. Public exploit reference

Software pages

PHP vulnerabilities

Related CVEs

CVE-2020-20977 MEDIUM 5.4 DOWNGRADE A stored cross site scripting (XSS) vulnerability in index.php/legend/6.html of UK CMS v1.1.10 allows attacker

References

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