CVE-2026-25793 PUBLISHED

Nebula Has Possible Blocklist Bypass via ECDSA Signature Malleability

Assigner: GitHub_M
Reserved: 05.02.2026 Published: 06.02.2026 Updated: 06.02.2026

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.

Metrics

CVSS 4.0

CVSS Vector: 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
CVSS Score: 7.6

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	High	Confidentiality	None
Attack Complexity	Low	Integrity	High	Integrity	None
Attack Requirements	Present	Availability	None	Availability	None
Privileges Required	Low
User Interaction	None

CVSS 4.0

Product Status

Vendor	slackhq
Product	nebula
Versions	Version >= 1.7.0, < 1.10.3 is affected

References

Problem Types

CWE-347: Improper Verification of Cryptographic Signature CWE