Vulnerability record · CVE-2026-25793 · published 6 February 2026

CVE-2026-25793: Slack nebula improper verification of cryptographic signature vulnerability

Slack · Nebula

Nebula is a scalable overlay networking tool. In versions from 1.7.0 to 1.10.2, when using P256 certificates (which is not the default configuration), it is possible to evade a blocklist entry created against the fingerprint of a certificate by using ECDSA Signature Malleability to use a copy of the certificate with a different fingerprint. This issue has been patched in version 1.10.3.

7.6 CVSS 4.0 High EPSS 0.17% · top 94.3% CWE-347 · Improper verification of cryptographic signature

7.6CVSS 4.0 base score

0.17%EPSS exploitation probability, 30 days

NoNot in CISA KEV

1Affected product versions listed by NVD

2References

17 Jun 2026Last modified by NVD

Description

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

Nebula Slack

References

Link	Tags
https://github.com/slackhq/nebula/commit/f573e8a26695278f9d71587390fbfe0d0933aa21	Patch
https://github.com/slackhq/nebula/security/advisories/GHSA-69x3-g4r3-p962	Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-25793), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.