CVE-2013-4100: Cryptocat before 2.0.22 has Remote Denial of Service via username

Q: How do I fix CVE-2013-4100?

cryptocat: upgrade to 2.0.22. Exact commands for each OS are on this page.

Q: Is CVE-2013-4100 being exploited?

CVE-2013-4100 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2013-4100 affect?

CVE-2013-4100 affects cryptocat. Severity is high (CVSS 7.5). Cryptocat before 2.0.22 has Remote Denial of Service via username

Q: How urgent is CVE-2013-4100?

Priority 52/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTEUPGRADE

CVE-2013-4100 is a high-severity flaw (CVSS 7.5) affecting cryptocat. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cryptocat before 2.0.22 has Remote Denial of Service via username

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.4% (top 16%)
CISA exploited list	No
Weakness	CWE-20
Published	2019-11-04
Last modified	2026-06-16

Publisher (CNA): Red Hat, Inc. · Vendor: cryptocat project

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-11-04 15:15 UTCPublished CVE record published
2026-06-16 23:56 UTCUpdated Record last modified

cryptocat project cryptocat UPGRADE

Affected: < 2.0.22

Fixed in: 2.0.22

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 2.0.22 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade cryptocat

Note

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

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-2013-4100?

cryptocat: upgrade to 2.0.22. Exact commands for each OS are on this page.

Is CVE-2013-4100 being exploited?

CVE-2013-4100 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-2013-4100 affect?

CVE-2013-4100 affects cryptocat. Severity is high (CVSS 7.5). Cryptocat before 2.0.22 has Remote Denial of Service via username

How urgent is CVE-2013-4100?

Priority 52/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2013-4110 MEDIUM 5.3 MITIGATE Cryptocat has an Unspecified Chat Participant User List Disclosure
CVE-2013-4109 MEDIUM 6.1 DOWNGRADE An unspecified cross-site scripting (XSS) vulnerability exists in Cryptocat Message Handling 1.1.165.
CVE-2013-4108 CRITICAL 9.8 DOWNGRADE Multiple unspecified vulnerabilities in Cryptocat Project Cryptocat 2.0.18 have unknown impact and attack vect
CVE-2013-4107 MEDIUM 6.1 UPGRADE Cryptocat before 2.0.22: cryptocat.js handlePresence() has cross site scripting
CVE-2013-4106 MEDIUM 6.1 UPGRADE A Cross-site scripting (XSS) vulnerability exists in Conversation Overview Nickname in Cryptocat before 2.0.22

References

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