How severe is CVE-2026-21874?

CVE-2026-21874 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2026-21874 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21874?

CVE-2026-21874 affects Zauberzeug Nicegui. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-21874?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-21874 have an EU (EUVD) identifier?

Yes. CVE-2026-21874 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1474.

When was CVE-2026-21874 published?

CVE-2026-21874 was published on 2026-01-08 and last updated on 2026-06-17.

CVE-2026-21874

CVE-2026-21874 is a medium-severity vulnerability in Zauberzeug Nicegui with a CVSS 3.x base score of 5.3. 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-772.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 1% (40th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-1474
Weakness: CWE-772
Affected product: Zauberzeug Nicegui
Published: 2026-01-08
Last modified: 2026-06-17

Description

NiceGUI is a Python-based UI framework. From versions v2.10.0 to 3.4.1, an unauthenticated attacker can exhaust Redis connections by repeatedly opening and closing browser tabs on any NiceGUI application using Redis-backed storage. Connections are never released, leading to service degradation when Redis hits its connection limit. NiceGUI continues accepting new connections - errors are logged but the app stays up with broken storage functionality. This issue has been patched in version 3.5.0.

Frequently asked questions

What is CVE-2026-21874?: NiceGUI is a Python-based UI framework. From versions v2.10.0 to 3.4.1, an unauthenticated attacker can exhaust Redis connections by repeatedly opening and closing browser tabs on any NiceGUI application using Redis-backed storage. Connections are never released, leading to service degradation when Redis hits its connection limit. NiceGUI continues accepting new connections - errors are logged but the app stays up with broken storage functionality. This issue has been patched in version 3.5.0.
How severe is CVE-2026-21874?: CVE-2026-21874 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2026-21874 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21874?: CVE-2026-21874 affects Zauberzeug Nicegui. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-21874?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-21874 have an EU (EUVD) identifier?: Yes. CVE-2026-21874 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1474.
When was CVE-2026-21874 published?: CVE-2026-21874 was published on 2026-01-08 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:zauberzeug:nicegui:*:*:*:*:*:*:*:*

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