How severe is CVE-2026-20421?

CVE-2026-20421 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-20421 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-20421?

CVE-2026-20421 affects Mediatek Nr15. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-20421?

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

Does CVE-2026-20421 have an EU (EUVD) identifier?

Yes. CVE-2026-20421 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5147.

When was CVE-2026-20421 published?

CVE-2026-20421 was published on 2026-02-02 and last updated on 2026-06-17.

CVE-2026-20421

CVE-2026-20421 is a medium-severity vulnerability in Mediatek Nr15 with a CVSS 3.x base score of 6.5. 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-125.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (12th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-5147
Weakness: CWE-125
Affected product: Mediatek Nr15
Published: 2026-02-02
Last modified: 2026-06-17

Description

In Modem, there is a possible system crash due to improper input validation. This could lead to remote denial of service, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: MOLY01738293; Issue ID: MSV-5922.

Frequently asked questions

What is CVE-2026-20421?: In Modem, there is a possible system crash due to improper input validation. This could lead to remote denial of service, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: MOLY01738293; Issue ID: MSV-5922.
How severe is CVE-2026-20421?: CVE-2026-20421 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-20421 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-20421?: CVE-2026-20421 affects Mediatek Nr15. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-20421?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-20421 have an EU (EUVD) identifier?: Yes. CVE-2026-20421 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5147.
When was CVE-2026-20421 published?: CVE-2026-20421 was published on 2026-02-02 and last updated on 2026-06-17.

References

https://corp.mediatek.com/product-security-bulletin/February-2026

Affected products (1)

cpe:2.3:o:mediatek:nr15:-:*:*:*:*:*:*:*

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