CVE-2021-41867: An information disclosure vulnerability in OnionShare 2.3 before 2.4 allows remote unauthenticated attackers t

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MEDIUM 5.3REMOTEUPGRADE

CVE-2021-41867 is a medium-severity flaw (CVSS 5.3) affecting onionshare. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An information disclosure vulnerability in OnionShare 2.3 before 2.4 allows remote unauthenticated attackers to retrieve the full list of participants of a non-public OnionShare node via the --chat feature.

Why this priority

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

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.8% (top 21%)
CISA exploited list	No
Published	2021-10-04
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: onionshare

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

Am I affected?

Timeline

2021-10-04 14:15 UTCPublished CVE record published
2026-06-17 04:09 UTCUpdated Record last modified

onionshare onionshare UPGRADE

Affected: >= 2.3 and < 2.4

Fixed in: 2.4

Safe to downgrade to: a release before 2.3

1. Check installed version

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

2. UPGRADE to 2.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade onionshare

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade onionshare

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.3 (Debian / Ubuntu)

apt-cache madison onionshare sudo apt install onionshare=<VERSION_BEFORE_2.3> sudo apt-mark hold onionshare

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list onionshare sudo dnf downgrade onionshare-<VERSION_BEFORE_2.3> sudo dnf versionlock add onionshare

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-2021-41867?

onionshare: upgrade to 2.4. Exact commands for each OS are on this page.

Is CVE-2021-41867 being exploited?

CVE-2021-41867 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-2021-41867 affect?

CVE-2021-41867 affects onionshare. Severity is medium (CVSS 5.3). An information disclosure vulnerability in OnionShare 2.3 before 2.4 allows remote unauthenticated attackers to retrieve the full list of participants of a non-public OnionShare node via the --chat feature.

How urgent is CVE-2021-41867?

Priority 48/100. Public exploit reference; Remotely exploitable, no login, no user action

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References

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