CVE-2018-20423: Discuz! DiscuzX 3.4, when WeChat login is enabled, allows remote attackers to bypass a "disabled registration"

This week

HIGH 8.1REMOTEDOWNGRADE

CVE-2018-20423 is a high-severity flaw (CVSS 8.1) affecting discuzx. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Discuz! DiscuzX 3.4, when WeChat login is enabled, allows remote attackers to bypass a "disabled registration" setting by adding a non-existing wxopenid value to the plugin.php ac=wxregister query string.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	1.2% (top 32%)
CISA exploited list	No
Published	2018-12-24
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: comsenz

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

Am I affected?

Timeline

2018-12-24 04:29 UTCPublished CVE record published
2026-06-17 01:52 UTCUpdated Record last modified

comsenz discuzx DOWNGRADE

Affected: x3.4

Fixed in: no fixed release known

Safe to downgrade to: a release before x3.4

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before x3.4 (Debian / Ubuntu)

apt-cache madison discuzx sudo apt install discuzx=<VERSION_BEFORE_x3.4> sudo apt-mark hold discuzx

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

dnf --showduplicates list discuzx sudo dnf downgrade discuzx-<VERSION_BEFORE_x3.4> sudo dnf versionlock add discuzx

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-2018-20423?

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

Is CVE-2018-20423 being exploited?

CVE-2018-20423 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-2018-20423 affect?

CVE-2018-20423 affects discuzx. Severity is high (CVSS 8.1). Discuz! DiscuzX 3.4, when WeChat login is enabled, allows remote attackers to bypass a "disabled registration" setting by adding a non-existing wxopenid value to the plugin.php ac=wxregister query string.

How urgent is CVE-2018-20423?

Priority 55/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities

Related CVEs

CVE-2024-30884 HIGH 7.1 DOWNGRADE Reflected Cross-Site Scripting (XSS) vulnerability in Discuz! version X3.4 20220811, allows remote attackers t
CVE-2022-45543 MEDIUM 6.1 DOWNGRADE Cross site scripting (XSS) vulnerability in DiscuzX 3.4 allows attackers to execute arbitrary code via the dat
CVE-2018-5377 CRITICAL 9.8 DOWNGRADE Discuz! DiscuzX X3.4 allows remote attackers to bypass intended access restrictions via the archiver\index.php
CVE-2018-5376 MEDIUM 6.1 DOWNGRADE Discuz! DiscuzX X3.4 has XSS via the include\spacecp\spacecp_upload.php op parameter.
CVE-2018-5375 MEDIUM 6.1 DOWNGRADE Discuz! DiscuzX X3.4 has XSS via the include\spacecp\spacecp_space.php appid parameter in a delete action.

References

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