CVE-2026-53603
HIGHDescription
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 to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v4 Vector
Exploitability
Impact
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
Exploit Intelligence
Low risk: more likely to be exploited than 11% of all known CVEs.
References
Related Vulnerabilities
Other CWE-312 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-50719 | High | 7.5 | 84% | - | Fix |
| CVE-2022-26148 | Critical | 9.8 | 53% | - | Fix |
| CVE-2020-24577 | High | 7.5 | 19% | - | Fix |
| CVE-2021-27140 | High | 7.5 | 19% | - | - |
| CVE-2021-27176 | High | 7.5 | 19% | - | - |
| CVE-2021-27174 | High | 7.5 | 19% | - | - |
Common questions
How do I fix CVE-2026-53603?
No published fix for CVE-2026-53603 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-53603 being actively exploited?
Not that we know of. CVE-2026-53603 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.20% is the estimated probability that it will be exploited in the next 30 days. That is higher than 11% of all scored CVEs.
How severe is CVE-2026-53603?
CVE-2026-53603 has a CVSS v4 base score of 7.1, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-08.