EUVD-2026-62244Severity by source
AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Race condition requiring two stack switches within a narrow lock-release window warrants AC:H; local unprivileged account maps to AV:L/PR:N with full C/I/A impact from privilege escalation.
Primary rating from Vendor (freebsd).
CVSS VectorVendor: freebsd
Lifecycle Timeline
3DescriptionCVE.org
The RACK setsockopt(2) handler drops the connection lock in order to copy option data from userspace, then reacquires the lock. After reacquiring, it verifies that the TCP stack had not been switched away, but did not reload its pointer to the stack's per-connection control block. If userspace switches stacks twice during this window, the check will succeed but the saved pointer will refer to freed memory.
The bug may be exploitable by an unprivileged local user to escalate privileges.
AnalysisAI
Privilege escalation in FreeBSD's RACK TCP stack via a use-after-free condition allows an unprivileged local user to achieve full system compromise. The RACK setsockopt(2) handler temporarily releases the connection lock while copying option data from userspace; if a concurrent context switches TCP stacks twice during this window, the stale saved pointer to the per-connection control block references freed memory while the integrity check erroneously passes. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a local user account on a FreeBSD system (no network-only access path exists; AV:L confirmed by CVSS vector). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The official CVSS base score of 8.4 (AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) reflects local access by an unprivileged user yielding full system impact, which is directionally correct given the privilege escalation outcome. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Apply the vendor-released patches to bring affected systems to FreeBSD 14.3-RELEASE-p16, 14.4-RELEASE-p7, 15.0-RELEASE-p11, or 15.1-RELEASE-p1 respectively, as detailed in FreeBSD Security Advisory FreeBSD-SA-26:43.tcp at https://security.freebsd.org/advisories/FreeBSD-SA-26:43.tcp.asc. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all FreeBSD systems running versions 14.3, 14.4, 15.0, or 15.1 and classify by data sensitivity and user access permissions. …
Sign in for detailed remediation steps and compensating controls.
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Same weakness CWE-416 – Use After Free
View allSame technique Use After Free
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External POC / Exploit Code
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