CVE-2023-34461: PyBB is an open source bulletin board

Routine

MEDIUM 4.6DOWNGRADE

CVE-2023-34461 is a medium-severity flaw (CVSS 4.6) affecting pybb. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

PyBB is an open source bulletin board. A manual code review of the PyBB bulletin board server has revealed that a vulnerability could have been exploited in which users could submit any type of HTML tag, and have said tag run. For example, a malicious `<a>` that looks like ```<a href=javascript:alert (1)>xss</a>``` could have been used to run code through JavaScript on the client side. The problem has been patched as of commit `5defd92`, and user

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	4.6 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.3% (top 73%)
CISA exploited list	No
Weakness	CWE-79
Published	2023-06-19
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: pybb project

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

Am I affected?

Timeline

2023-06-19 18:15 UTCPublished CVE record published
2026-06-17 06:03 UTCUpdated Record last modified

pybb project pybb DOWNGRADE

Affected: 0.1.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.1.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.1.0 (Debian / Ubuntu)

apt-cache madison pybb sudo apt install pybb=<VERSION_BEFORE_0.1.0> sudo apt-mark hold pybb

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

dnf --showduplicates list pybb sudo dnf downgrade pybb-<VERSION_BEFORE_0.1.0> sudo dnf versionlock add pybb

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-2023-34461?

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

Is CVE-2023-34461 being exploited?

CVE-2023-34461 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-2023-34461 affect?

CVE-2023-34461 affects pybb. Severity is medium (CVSS 4.6). PyBB is an open source bulletin board. A manual code review of the PyBB bulletin board server has revealed that a vulnerability could have been exploited in which users could submit any type of HTML tag, and have said tag run. For example,

How urgent is CVE-2023-34461?

Priority 23/100. No elevated risk signals yet.

Related CVEs

CVE-2023-34249 CRITICAL 9.8 UPGRADE benjjvi/PyBB is an open source bulletin board

References

← Back to latest CVEs