CVE-2021-33840: The server in Luca through 1.1.14 allows remote attackers to cause a denial of service (insertion of many fake

Q: How do I fix CVE-2021-33840?

luca: upgrade to newer than 1.1.14. Exact commands for each OS are on this page.

Q: Is CVE-2021-33840 being exploited?

CVE-2021-33840 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-2021-33840 affect?

CVE-2021-33840 affects luca. Severity is high (CVSS 7.5). The server in Luca through 1.1.14 allows remote attackers to cause a denial of service (insertion of many fake records related to COVID-19) because Phone Number data lacks a digital signature.

Q: How urgent is CVE-2021-33840?

Priority 46/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTEUPGRADE

CVE-2021-33840 is a high-severity flaw (CVSS 7.5) affecting luca. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The server in Luca through 1.1.14 allows remote attackers to cause a denial of service (insertion of many fake records related to COVID-19) because Phone Number data lacks a digital signature.

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	0.9% (top 40%)
CISA exploited list	No
Weakness	CWE-345
Published	2021-06-04
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: luca-app

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

Am I affected?

Timeline

2021-06-04 00:15 UTCPublished CVE record published
2026-06-17 03:55 UTCUpdated Record last modified

luca-app luca UPGRADE

Affected: <= 1.1.14

Fixed in: newer than 1.1.14

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 1.1.14 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade luca

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-2021-33840?

luca: upgrade to newer than 1.1.14. Exact commands for each OS are on this page.

Is CVE-2021-33840 being exploited?

CVE-2021-33840 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-2021-33840 affect?

CVE-2021-33840 affects luca. Severity is high (CVSS 7.5). The server in Luca through 1.1.14 allows remote attackers to cause a denial of service (insertion of many fake records related to COVID-19) because Phone Number data lacks a digital signature.

How urgent is CVE-2021-33840?

Priority 46/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-33839 HIGH 7.5 UPGRADE Luca through 1.7.4 on Android allows remote attackers to obtain sensitive information about COVID-19 tracking
CVE-2021-33838 HIGH 7.5 UPGRADE Luca through 1.7.4 on Android allows remote attackers to obtain sensitive information about COVID-19 tracking

References

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