CVE-2021-3297 in the critical feed json
On Zyxel NBG2105 V1.00(AAGU.2)C0 devices, setting the login cookie to 1 provides administrator access.
published 2021-01-26 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26631
- cvss
- 7.8
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 20.5%
- EPSS 20.5% chance of exploitation in 30 days, percentile 97%
- public exploits
- 0
- none known, plus a Nuclei check
Summary
On Zyxel NBG2105 V1.00(AAGU.2)C0 devices, setting the login cookie to 1 provides administrator access.
Exploit prediction
20.51% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- Nuclei template Zyxel NBG2105 V1.00(AAGU.2)C0 - Authentication Bypass nuclei detection template
- github.com https://github.com/nieldk/vulnerabilities/blob/main/zyxel%20nbg2105/Admin%20bypass referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVD | 2.0 | 7.2 | AV:L/AC:L/Au:N/C:C/I:C/A:C |
Classification
- Weakness
-
- CWE-287 Improper Authentication
References
-
github.com
/nieldk/vulnerabilities/blob/main/zyxel%20nbg2105/Admin%20bypass
exploit, third-party-advisory
-
zyxel.com
/us/en/support/security_advisories.shtml
vendor-advisory
-
zyxel.com
/support/SupportLandingSR.shtml?c=gb&l=en&kbid=M-01490&md=NBG2105
product, vendor-advisory
- codeberg.org /nieldk/vulnerabilities/src/branch/main/zyxel%20nbg2105/Admin%20bypass
Sources
- CVE List CVE-2021-3297
- NVD CVE-2021-3297
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.