How severe is CVE-2021-3297?

CVE-2021-3297 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-3297 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 21% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3297?

CVE-2021-3297 affects Zyxel Nbg2105 Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3297?

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-2021-3297 published?

CVE-2021-3297 was published on 2021-01-26 and last updated on 2026-06-17.

CVE-2021-3297

CVE-2021-3297 is a high-severity vulnerability in Zyxel Nbg2105 Firmware with a CVSS 3.x base score of 7.8. Its EPSS exploit-prediction score of 21% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-287.

Key facts

Severity: High (CVSS 3.x base score 7.8)
CVSS v2: 7.2
EPSS exploit prediction: 21% (97th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Zyxel Nbg2105 Firmware
Published: 2021-01-26
Last modified: 2026-06-17

Description

On Zyxel NBG2105 V1.00(AAGU.2)C0 devices, setting the login cookie to 1 provides administrator access.

Frequently asked questions

What is CVE-2021-3297?: On Zyxel NBG2105 V1.00(AAGU.2)C0 devices, setting the login cookie to 1 provides administrator access.
How severe is CVE-2021-3297?: CVE-2021-3297 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-3297 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 21% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3297?: CVE-2021-3297 affects Zyxel Nbg2105 Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3297?: 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-2021-3297 published?: CVE-2021-3297 was published on 2021-01-26 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:zyxel:nbg2105_firmware:v1.00\(aagu.2\)c0:*:*:*:*:*:*:*

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