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Slack Nebula may accept arbitrary source IP addresses

Moderate severity GitHub Reviewed Published Oct 23, 2025 to the GitHub Advisory Database • Updated Oct 23, 2025

Package

gomod github.com/slackhq/nebula (Go)

Affected versions

>= 1.9.4, < 1.9.7

Patched versions

1.9.7

Description

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

References

Published by the National Vulnerability Database Oct 23, 2025
Published to the GitHub Advisory Database Oct 23, 2025
Reviewed Oct 23, 2025
Last updated Oct 23, 2025

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:L

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(11th percentile)

Weaknesses

Unprotected Alternate Channel

The product protects a primary channel, but it does not use the same level of protection for an alternate channel. Learn more on MITRE.

CVE ID

CVE-2025-62820

GHSA ID

GHSA-x6fh-7qmf-69xh

Source code

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