CVE-2020-5842: Codoforum 4.8.3 allows XSS in the user registration page: via the username field to the index.php?u=/user/regi

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MEDIUM 6.1DOWNGRADE

CVE-2020-5842 is a medium-severity flaw (CVSS 6.1) affecting codoforum. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Codoforum 4.8.3 allows XSS in the user registration page: via the username field to the index.php?u=/user/register URI. The payload is, for example, executed on the admin/index.php?page=users/manage page.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.8% (top 21%)
CISA exploited list	No
Weakness	CWE-79
Published	2020-01-07
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: codologic

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

Am I affected?

Timeline

2020-01-07 20:15 UTCPublished CVE record published
2026-06-17 03:22 UTCUpdated Record last modified

codologic codoforum DOWNGRADE

Affected: 4.8.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.8.3

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.8.3 (Debian / Ubuntu)

apt-cache madison codoforum sudo apt install codoforum=<VERSION_BEFORE_4.8.3> sudo apt-mark hold codoforum

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

dnf --showduplicates list codoforum sudo dnf downgrade codoforum-<VERSION_BEFORE_4.8.3> sudo dnf versionlock add codoforum

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-2020-5842?

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

Is CVE-2020-5842 being exploited?

CVE-2020-5842 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-2020-5842 affect?

CVE-2020-5842 affects codoforum. Severity is medium (CVSS 6.1). Codoforum 4.8.3 allows XSS in the user registration page: via the username field to the index.php?u=/user/register URI. The payload is, for example, executed on the admin/index.php?page=users/manage page.

How urgent is CVE-2020-5842?

Priority 46/100. Public exploit reference

Software pages

PHP vulnerabilities

Related CVEs

CVE-2022-31854 HIGH 7.2 DOWNGRADE Codoforum v5.1 was discovered to contain an arbitrary file upload vulnerability via the logo change option in
CVE-2020-9007 MEDIUM 5.4 DOWNGRADE Codoforum 4.8.8 allows self-XSS via the title of a new topic.
CVE-2020-7051 MEDIUM 6.1 UPGRADE Codologic Codoforum through 4.8.4 allows stored XSS in the login area
CVE-2020-7050 MEDIUM 5.4 UPGRADE Codologic Codoforum through 4.8.4 allows a DOM-based XSS
CVE-2020-5843 MEDIUM 4.8 DOWNGRADE Codoforum 4.8.3 allows XSS in the admin dashboard via a category to the Manage Users screen.

References

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