CVE-2018-25309: MyBB Recent threads 17.0 contains a persistent cross-site scripting vulnerability that allows attackers to inj

This week

HIGH 7.2REMOTEDOWNGRADE

CVE-2018-25309 is a high-severity flaw (CVSS 7.2) affecting recent threads on index. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

MyBB Recent threads 17.0 contains a persistent cross-site scripting vulnerability that allows attackers to inject malicious scripts by creating threads with crafted subject lines. Attackers can create threads with script tags in the subject parameter to execute arbitrary JavaScript in the browsers of all users viewing the index page.

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	7.2 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 82%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-04-29
Last modified	2026-06-17

Publisher (CNA): VulnCheck · Vendor: dragonexpert

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

Am I affected?

Timeline

2026-04-29 20:16 UTCPublished CVE record published
2026-06-17 01:55 UTCUpdated Record last modified

dragonexpert recent threads on index DOWNGRADE

Affected: 17.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 17.0

1. Check installed version

apt-cache policy recent-threads-on-index || rpm -q recent-threads-on-index || recent-threads-on-index --version

2. No fixed release: DOWNGRADE to a release before 17.0 (Debian / Ubuntu)

apt-cache madison recent-threads-on-index sudo apt install recent-threads-on-index=<VERSION_BEFORE_17.0> sudo apt-mark hold recent-threads-on-index

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

dnf --showduplicates list recent-threads-on-index sudo dnf downgrade recent-threads-on-index-<VERSION_BEFORE_17.0> sudo dnf versionlock add recent-threads-on-index

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-2018-25309?

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

Is CVE-2018-25309 being exploited?

CVE-2018-25309 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-2018-25309 affect?

CVE-2018-25309 affects recent threads on index. Severity is high (CVSS 7.2). MyBB Recent threads 17.0 contains a persistent cross-site scripting vulnerability that allows attackers to inject malicious scripts by creating threads with crafted subject lines. Attackers can create threads with script tags in the subject

How urgent is CVE-2018-25309?

Priority 40/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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