EUVD-2026-26353Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
8DescriptionCVE.org
An operator precedence bug in the kernel results in a scenario where a buffer overflow causes attacker-controlled data to overwrite adjacent execve(2) argument buffers.
The bug may be exploitable by an unprivileged user to obtain superuser privileges.
AnalysisAI
Local privilege escalation in FreeBSD kernel allows authenticated users to gain root privileges through buffer overflow in execve(2) argument handling. The vulnerability stems from an operator precedence bug causing attacker-controlled data to overwrite adjacent execution argument buffers. CISA SSVC framework indicates no active exploitation detected, though the technical impact enables complete system compromise. EPSS probability remains very low (0.02%, 5th percentile), suggesting targeted rather than widespread threat. FreeBSD has released patches across all supported release branches.
Technical ContextAI
The vulnerability exists in the FreeBSD kernel's execve(2) system call implementation, specifically in how it handles argument buffer allocation and copying. An operator precedence error in the kernel code creates a condition where buffer boundaries are incorrectly calculated, allowing an overflow to propagate into adjacent memory regions containing execve arguments. This is classified as CWE-783 (Operator Precedence Logic Error), a subtle programming mistake where incorrect operator evaluation order leads to unintended computation results. The execve(2) system call is fundamental to process execution in Unix-like systems, making it a high-value target. The bug affects the kernel's memory management logic during process creation, where argument vectors are prepared in kernel space before transitioning to the new process context. The CPE identifier (cpe:2.3:a:freebsd:freebsd) confirms this impacts the FreeBSD operating system kernel itself across multiple major release branches (13.x, 14.x, and 15.x).
RemediationAI
Apply vendor-released patches immediately via freebsd-update utility or rebuild kernel from patched sources. For FreeBSD 14.3-RELEASE, upgrade to patch level p12 or higher; for FreeBSD 13.5-RELEASE, upgrade to p13 or higher; for FreeBSD 14.4-RELEASE, upgrade to p3 or higher; for FreeBSD 15.0-RELEASE, upgrade to p7 or higher. Execute 'freebsd-update fetch' followed by 'freebsd-update install' and reboot to activate patched kernel. Systems unable to patch immediately should implement compensating controls: restrict local user access through stricter authentication policies, disable unnecessary user accounts, enable and monitor kernel security event auditing (auditd) to detect unusual execve patterns, and consider deploying mandatory access control frameworks (MAC) like TrustedBSD to limit privilege escalation paths. Note that MAC policies may impact application compatibility and require testing. Source code patches available through FreeBSD source repository for custom kernel builds. Complete remediation guidance at https://security.freebsd.org/advisories/FreeBSD-SA-26:13.exec.asc including verification procedures.
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Same weakness CWE-783 – Operator Precedence Logic Error
View allSame technique Buffer Overflow
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External POC / Exploit Code
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