What is CVE-2025-62820?

CVE-2025-62820 is a medium-severity vulnerability in Slack Nebula, classified under Unprotected Alternate Channel. CVSS score: 4.9/10. Published 2025-10-23.

How severe is CVE-2025-62820?

Medium severity. CVSS v3 base score is 4.9 out of 10.

Vulnerability in Slack Nebula

CVE-2025-62820

Slack Nebula before 1.9.7 mishandles CIDR in some configurations and thus accepts arbitrary source IP addresses within the Nebula network.

EPSS: 0.002 (10.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:L.

Affected products

Slack Nebula — versions 0

Weakness classification (CWE)

CWE-420 — Unprotected Alternate Channel

References

cve@mitre.org
cve@mitre.org

Frequently asked questions

What is CVE-2025-62820?: CVE-2025-62820 is a medium-severity vulnerability in Slack Nebula, classified under Unprotected Alternate Channel. CVSS score: 4.9/10. Published 2025-10-23.
How severe is CVE-2025-62820?: Medium severity. CVSS v3 base score is 4.9 out of 10.