CVE-2021-41055: Gajim 1.2.x and 1.3.x before 1.3.3 allows remote attackers to cause a denial of service (crash) via a crafted

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HIGH 7.5REMOTEUPGRADE

CVE-2021-41055 is a high-severity flaw (CVSS 7.5) affecting gajim. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Gajim 1.2.x and 1.3.x before 1.3.3 allows remote attackers to cause a denial of service (crash) via a crafted XMPP Last Message Correction (XEP-0308) message in multi-user chat, where the message ID equals the correction ID.

Why this priority

High severity
Public exploit reference
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	1.6% (top 25%)
CISA exploited list	No
Published	2021-10-11
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: gajim

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

Am I affected?

Timeline

2021-10-11 03:15 UTCPublished CVE record published
2026-06-17 04:07 UTCUpdated Record last modified

gajim gajim UPGRADE

Affected: >= 1.2.0 and < 1.3.3

Fixed in: 1.3.3

Safe to downgrade to: a release before 1.2.0

1. Check installed version

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

2. UPGRADE to 1.3.3 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade gajim

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 1.2.0 (Debian / Ubuntu)

apt-cache madison gajim sudo apt install gajim=<VERSION_BEFORE_1.2.0> sudo apt-mark hold gajim

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

dnf --showduplicates list gajim sudo dnf downgrade gajim-<VERSION_BEFORE_1.2.0> sudo dnf versionlock add gajim

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-2021-41055?

gajim: upgrade to 1.3.3. Exact commands for each OS are on this page.

Is CVE-2021-41055 being exploited?

CVE-2021-41055 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-2021-41055 affect?

CVE-2021-41055 affects gajim. Severity is high (CVSS 7.5). Gajim 1.2.x and 1.3.x before 1.3.3 allows remote attackers to cause a denial of service (crash) via a crafted XMPP Last Message Correction (XEP-0308) message in multi-user chat, where the message ID equals the correction ID.

How urgent is CVE-2021-41055?

Priority 55/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2022-39835 MEDIUM 5.3 UPGRADE An issue was discovered in Gajim through 1.4.7

References

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