7.8

CVE-2021-3297: zyxel nbg2105_firmware Improper Authentication

CVSS: 7.8v3.1HighModified
Published 26-01-2021Last modified 25-11-2025
Open JSON

Vulnerability summary

CVE-2021-3297 is a high (CVSS 7.8) Improper Authentication vulnerability in zyxel nbg2105_firmware. EPSS estimates a 20.51% chance of exploitation in the next 30 days, higher than 97.4% of scored vulnerabilities. 1 public exploit is recorded.

Overall risk
45/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.8/10
010
High · v3.1 (NVD)
EPSS score
20.51%
0%100%
High · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1github

Timeline

  1. 26-01-2021
    PublishedVulnerability first disclosed.
  2. 25-11-2025
    Last modifiedVulnerability information updated.

Description

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

CVSS metrics

2 scores · 1 source · 2 versions

EPSS trend

Probability

20.51%

Chance of exploitation in the next 30 days

Percentile

97%

Versus all other CVEs

30-day change

0.00 pp

From 20.51% on 19-09-2026

19-09-202619-10-2026
EPSS score
20.51%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

1 found
  • githubUnverified

    Vulnerabilities

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Zyxel1 product

1 vendor · 1 product

References

4 links