How severe is CVE-2021-33839?

CVE-2021-33839 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-33839 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33839?

CVE-2021-33839 affects Luca-app Luca. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-33839?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-33839 published?

CVE-2021-33839 was published on 2021-06-04 and last updated on 2026-06-17.

CVE-2021-33839

CVE-2021-33839 is a high-severity vulnerability in Luca-app Luca with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-200.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 3% (85th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-200
Affected product: Luca-app Luca
Published: 2021-06-04
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-33839?: 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 severe is CVE-2021-33839?: CVE-2021-33839 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-33839 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33839?: CVE-2021-33839 affects Luca-app Luca. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-33839?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-33839 published?: CVE-2021-33839 was published on 2021-06-04 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:luca-app:luca:*:*:*:*:*:android:*:*

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CVE-2021-33840 — 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…
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