EUVD-2026-62351
GHSA-j94h-9p69-vhvm
Severity by source
AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Race condition between timer interrupt and fork() copy path justifies AC:H; PR:N confirmed by unprivileged trigger; full kernel compromise yields C:H/I:H/A:H.
Primary rating from Vendor (freebsd).
CVSS VectorVendor: freebsd
Lifecycle Timeline
4DescriptionCVE.org
While the kernel was copying knotes during fork, a knote with a timer-based filter could fire and be enqueued on the kqueue's active list before the copy was complete. The copy routine did not account for this and could enqueue the new knote a second time, corrupting the active list. In addition, the copy routine did not hold the appropriate locks while reading knote state, allowing further races.
An unprivileged local user can trigger a use-after-free in the kernel, potentially leading to privilege escalation.
AnalysisAI
Use-after-free in the FreeBSD 15.1-RELEASE kernel's kqueue subsystem allows an unprivileged local user to corrupt kernel memory and escalate privileges to root. During a fork() system call, the kernel's knote copy routine fails to hold appropriate locks while reading knote state, and does not guard against a timer-based knote firing and being enqueued on the active list mid-copy, resulting in a double-enqueue of the new knote and subsequent list corruption. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The attacker must have an unprivileged interactive or programmatic local session on a FreeBSD 15.1-RELEASE system running a kernel earlier than patch level 2. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H scores 8.4 and indicates a local, zero-privileges attack with no user interaction required and full confidentiality, integrity, and availability impact - consistent with a kernel privilege escalation. … 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 FreeBSD patch 15.1-RELEASE-p2, which addresses the locking deficiencies and double-enqueue race in the knote copy routine. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: inventory all FreeBSD 15.1-RELEASE systems across production and non-production environments; immediately restrict local shell access to trusted administrative staff only and audit active local user accounts for necessity. …
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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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