CVE-2026-61699

Published

04 September 2026

Modified

08 September 2026

CVSS Score v3.1 8.1

Click a component to see what it means

Raw vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS Score 0.0025 17th percentile

Risk Priority 58 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-61699 is a high-severity Improper Check for Certificate Revocation (CWE-299) vulnerability. Its CVSS base score is 8.1 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 17th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and IA-5 (Authenticator Management) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2026-71720

Vulnerability Data

nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. Prior to version 0.7.1, revocation is the only in-band mechanism that isolates a compromised/offboarded host from a Nebula mesh. Because the blocklist never reaches any peer's config.yml, a Blocked…

host retains full overlay reachability to every peer under its CA (and internal services on the mesh) for up to 30d (agent) / 365d (mobile). An attacker who exfiltrates host.key+host.crt can run stock slackhq/nebula directly, ignore the agent's 403/410 poll responses, and stay connected after the operator revokes the host. Operator-visible state (UI shows blocked, audit log records it) is misleading. This issue has been patched in version 0.7.1.

CWE(s): CWE-299 CWE-672

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation

Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.

attack.mitre.org →

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1203 Exploitation for Client Execution Execution

Adversaries may exploit software vulnerabilities in client applications to execute code.

attack.mitre.org →

T1210 Exploitation of Remote Services Lateral Movement

Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.

attack.mitre.org →

T1553 Subvert Trust Controls Defense Impairment

Adversaries may undermine security controls that will either warn users of untrusted activity or prevent execution of untrusted programs.

attack.mitre.org →

T1553.002 Code Signing Defense Impairment

Adversaries may create, acquire, or steal code signing materials to sign their malware or tools.

attack.mitre.org →

Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-42446Shared CWE-672

CVE-2025-55669Shared CWE-672

CVE-2024-49955Shared CWE-672

CVE-2026-33463Shared CWE-672

CVE-2025-11955Shared CWE-299

CVE-2025-30351Shared CWE-672

CVE-2025-53901Shared CWE-672

CVE-2026-68481Shared CWE-672

CVE-2025-36057Shared CWE-299

CVE-2024-4693Shared CWE-672

Affected Assets

Mitigating Controls

Control response

Prevent

Stop it (NIST 800-53)

—

Detect

Catch it (NIST detect / respond)

—

Harden

Shrink the surface (DISA STIG)

1 hardening rule · 1 OS baseline

Validate

Prove the fix (OWASP ASVS)

V12.1.4

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match

Access enforcement applies current authorizations to every request, directly blocking operations once a resource has been revoked or released.

IA-5 Authenticator Management good match

Authenticator management mandates revocation and replacement procedures that render expired credentials unusable.

AC-2 Account Management partial match

Account lifecycle management includes explicit revocation and disabling steps that stop subsequent operations on released accounts or identifiers.

IA-4 Identifier Management partial match

Identifier management requires deallocation and reuse controls that prevent continued use of released identifiers.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-03 partial match

prevents

Certificate-based authentication requires valid, non-revoked certificates; proper revocation checking is a core implementation detail of this control.

PR.AA-05 partial match

prevents

Enforcing managed authorizations and revocations directly prevents post-release operations on credentials or entitlements.

PR.DS-02 partial match

prevents

Protecting data-in-transit commonly relies on TLS certificate validation that includes revocation status checks.

PR.PS-06 partial match

prevents

Secure development practices eliminate the root coding flaw that permits use-after-release.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.10 Information deletion partial match

degrades

Enforces timely deletion of resources so they cannot be used after release.

A.8.24 Use of cryptography partial match

prevents

Mandates use of cryptography including certificate validation and revocation checking.

A.8.28 Secure coding partial match

prevents

Secure coding practices should include proper certificate revocation verification.

A.8.29 Security testing in development and acceptance partial match

finds

Security testing can detect missing or incorrect certificate revocation checks.