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

Q: How do I fix CVE-2021-33839?

luca: upgrade to newer than 1.7.4. Exact commands for each OS are on this page.

Q: Is CVE-2021-33839 being exploited?

CVE-2021-33839 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-2021-33839 affect?

CVE-2021-33839 affects luca. Severity is high (CVSS 7.5). Luca through 1.7.4 on Android allows remote attackers to obtain sensitive information about COVID-19 tracking because the QR code of a Public Location can be intentionally confused with the QR code of a Private Meeting.

Q: How urgent is CVE-2021-33839?

Priority 58/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 7.5REMOTEUPGRADE

CVE-2021-33839 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.

Luca through 1.7.4 on Android allows remote attackers to obtain sensitive information about COVID-19 tracking because the QR code of a Public Location can be intentionally confused with the QR code of a Private Meeting.

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	2.8% (top 14%)
CISA exploited list	No
Weakness	CWE-200
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: <= 1.7.4

Fixed in: newer than 1.7.4

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 1.7.4 (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-2021-33839?

luca: upgrade to newer than 1.7.4. Exact commands for each OS are on this page.

Is CVE-2021-33839 being exploited?

CVE-2021-33839 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-2021-33839 affect?

CVE-2021-33839 affects luca. Severity is high (CVSS 7.5). Luca through 1.7.4 on Android allows remote attackers to obtain sensitive information about COVID-19 tracking because the QR code of a Public Location can be intentionally confused with the QR code of a Private Meeting.

How urgent is CVE-2021-33839?

Priority 58/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Android vulnerabilities

Related CVEs

CVE-2021-33840 HIGH 7.5 UPGRADE The server in Luca through 1.1.14 allows remote attackers to cause a denial of service (insertion of many fake
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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