How severe is CVE-2026-25793?

CVE-2026-25793 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-25793 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-25793?

CVE-2026-25793 affects Slack Nebula. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-25793?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-25793 have an EU (EUVD) identifier?

Yes. CVE-2026-25793 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-6933.

When was CVE-2026-25793 published?

CVE-2026-25793 was published on 2026-02-06 and last updated on 2026-06-17.

CVE-2026-25793

CVE-2026-25793 is a high-severity vulnerability in Slack Nebula with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-347.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v4: 7.6
EPSS exploit prediction: 0% (3rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-6933
Weakness: CWE-347
Affected product: Slack Nebula
Published: 2026-02-06
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-25793?: 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.
How severe is CVE-2026-25793?: CVE-2026-25793 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-25793 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-25793?: CVE-2026-25793 affects Slack Nebula. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-25793?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-25793 have an EU (EUVD) identifier?: Yes. CVE-2026-25793 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-6933.
When was CVE-2026-25793 published?: CVE-2026-25793 was published on 2026-02-06 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:slack:nebula:*:*:*:*:*:*:*:*

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