How severe is CVE-2026-25791?

CVE-2026-25791 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-25791 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-25791?

CVE-2026-25791 affects Bishopfox Sliver. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-25791?

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-2026-25791 have an EU (EUVD) identifier?

Yes. CVE-2026-25791 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-6853.

When was CVE-2026-25791 published?

CVE-2026-25791 was published on 2026-02-09 and last updated on 2026-06-17.

CVE-2026-25791

CVE-2026-25791 is a high-severity vulnerability in Bishopfox Sliver with a CVSS 3.x base score of 7.5. 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-306.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-6853
Weakness: CWE-306
Affected product: Bishopfox Sliver
Published: 2026-02-09
Last modified: 2026-06-17

Description

Sliver is a command and control framework that uses a custom Wireguard netstack. Prior to 1.7.0, the DNS C2 listener accepts unauthenticated TOTP bootstrap messages and allocates server-side DNS sessions without validating OTP values, even when EnforceOTP is enabled. Because sessions are stored without a cleanup/expiry path in this flow, an unauthenticated remote actor can repeatedly create sessions and drive memory exhaustion. This vulnerability is fixed in 1.7.0.

Frequently asked questions

What is CVE-2026-25791?: Sliver is a command and control framework that uses a custom Wireguard netstack. Prior to 1.7.0, the DNS C2 listener accepts unauthenticated TOTP bootstrap messages and allocates server-side DNS sessions without validating OTP values, even when EnforceOTP is enabled. Because sessions are stored without a cleanup/expiry path in this flow, an unauthenticated remote actor can repeatedly create sessions and drive memory exhaustion. This vulnerability is fixed in 1.7.0.
How severe is CVE-2026-25791?: CVE-2026-25791 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-25791 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-25791?: CVE-2026-25791 affects Bishopfox Sliver. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-25791?: 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-2026-25791 have an EU (EUVD) identifier?: Yes. CVE-2026-25791 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-6853.
When was CVE-2026-25791 published?: CVE-2026-25791 was published on 2026-02-09 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:bishopfox:sliver:*:*:*:*:*:*:*:*

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