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CVE-2026-53603

HIGHCVSS 7.1/10EPSS 0.20%

Last modified

CVE-2026-53603 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. Prior to version 0.3.8, Operator session tokens are stored in plaintext in the operator_sessions table (the token column is the PRIMARY KEY). EPSS estimates a 0.20% chance of exploitation in the next 30 days.

Description

nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. Prior to version 0.3.8, Operator session tokens are stored in plaintext in the operator_sessions table (the token column is the PRIMARY KEY). The session token is a 32-byte random hex value sent directly in a cookie and valid for 24 hours. Anyone who can read the database (backup, snapshot, file copy, or SQL-level disclosure) obtains every active session token and can hijack operator sessions directly, with no further authentication. This issue has been patched in version 0.3.8.

Metrics

CVSS 4.0
7.1/10

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability
0.20%

10.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
forgekeepnebula-mesh< 0.3.8

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-53603?
nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. Prior to version 0.3.8, Operator session tokens are stored in plaintext in the operator_sessions table (the token column is the PRIMARY KEY). The session token is a 32-byte random hex value sent directly in a cookie and valid for 24 hours. Anyone who can read the database (backup, snapshot, file copy, or SQL-level disclosure) obtains every active session token and can hijack operator sessions directly, with no further authentication. This issue has been patched in version 0.3.8.
How severe is CVE-2026-53603?
CVE-2026-53603 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 0.20% probability of exploitation in the next 30 days.
How do I fix CVE-2026-53603?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST