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01 Record

CVE-2023-35136

An improper input validation vulnerability in the “Quagga” package of the Zyxel ATP series firmware versions 4.32 through 5.37, USG FLEX series firmware versions 4.50 through 5.37, USG FLEX 50(W)

MediumPUBLISHEDCNA: Zyxel
CNA base score5.5 CVSS v3.xCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

02 Description

An improper input validation vulnerability in the “Quagga” package of the Zyxel ATP series firmware versions 4.32 through 5.37, USG FLEX series firmware versions 4.50 through 5.37, USG FLEX 50(W)

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.24% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 15.3% of scored records. A rank, not a probability.
NVD base score
5.5 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
NVD analysis status
Modified. NVD last modified this record on 2026-06-17.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2023-11-28 01:16Z2 YR AGO
Last updated
2025-06-05 13:54Z1 YR AGO
Reserved
2023-06-14
Assigning CNA
Zyxel
Record state
PUBLISHED
Severity
Medium (CVSS 5.5)
CNA CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Weaknesses
  • CWE-20Improper Input ValidationClass
Data version
5.1
Document digest
41f6668659cd73f7f598cc4154295f7f3b0ef8dbef871e982854d9c6e2690983

05 Affected products

VendorProductVersionsPlatforms
ZyxelATP series firmwareversions 4.32 through 5.37—
ZyxelUSG FLEX series firmwareversions 4.50 through 5.37—
ZyxelUSG FLEX 50(W) series firmwareversions 4.16 through 5.37—
ZyxelUSG20(W)-VPN series firmwareversions 4.16 through 5.37—
ZyxelVPN series firmwareversions 4.30 through 5.37—

06 References