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Fencer Vulns
medium 4.9

CVE-2025-62820 json

Slack Nebula may accept arbitrary source IP addresses

published 2025-10-23 12 mo ago modified 2026-10-08 31 d ago also GHSA-x6fh-7qmf-69xh , GO-2025-4068 , EUVD-2025-35657

cvss
4.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 12%
public exploits
0
none known

Summary

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

Patch / fix

  • go github.com/slackhq/nebula 1.9.7
  • Slack Nebula 1.9.7
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
  • govulncheck-vulndb openSUSE Tumbleweed 0.0.20251105T184115-1.1

opensuse advisories openSUSE-SU-2026:21483-1openSUSE-SU-2025:15710-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-62820 updated cvss 4.9

nebula: incorrect handling of CIDR in some configurations allows arbitrary source IP addresses within the network

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
12 mo ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.9 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:L
GitHub 3.1 4.9 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:L

Affected packages

ecosystem package affected fixed in
go github.com/slackhq/nebula
>=1.9.4, <1.9.7
1.9.7

Affected products

  • Slack Nebula

Classification

Weakness
  • CWE-420 Unprotected Alternate Channel

References

Sources

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.