CVE-2026-3870

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

0.17% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 6.5% of scored records. A rank, not a probability.

NVD base score

6.5 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD analysis status

Deferred. NVD last modified this record on 2026-07-22.

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.

Published

2026-06-02 01:54Z3 MO AGO

Last updated

2026-06-02 13:36Z3 MO AGO

Reserved

2026-03-10

Assigning CNA

Zyxel

Record state

PUBLISHED

Severity

Medium (CVSS 6.5)

CNA CVSS vector

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weaknesses

• CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')Base

Data version

5.2

Document digest

310d297e6d5f762667d67ee6d3add5c74442ddc55bf5a82a88fac872bf460773

• www.zyxel.comhttps://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-buffer-overflow-vulnerabilities-in-the-upnp-function-of-certain-4g-lte-5g-nr-cpe-and-dsl-ethernet-cpe-06-02-2026vendor-advisory