CVE-2018-5377: Discuz! DiscuzX X3.4 allows remote attackers to bypass intended access restrictions via the archiver\index.php

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2018-5377 is a critical-severity flaw (CVSS 9.8) affecting discuzx. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Discuz! DiscuzX X3.4 allows remote attackers to bypass intended access restrictions via the archiver\index.php action parameter.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.1% (top 18%)
CISA exploited list	No
Weakness	CWE-862
Published	2018-01-12
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: discuz

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

Am I affected?

Timeline

2018-01-12 09:29 UTCPublished CVE record published
2026-06-17 02:00 UTCUpdated Record last modified

discuz 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-2018-5377?

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

Is CVE-2018-5377 being exploited?

CVE-2018-5377 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-2018-5377 affect?

CVE-2018-5377 affects discuzx. Severity is critical (CVSS 9.8). Discuz! DiscuzX X3.4 allows remote attackers to bypass intended access restrictions via the archiver\index.php action parameter.

How urgent is CVE-2018-5377?

Priority 60/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities

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References

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