Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessObtain local unprivileged account
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DeliveryCall procctl(2) to disable ASLR
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Exploitexecve(2) setuid PIE binary
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ExecutionPIE loaded at predictable base
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PersistExploit separate memory-corruption bug
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ImpactEscalate to root
Vulnerability Assessment
| Weakness |
CWE
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| Exploitation Conditions | Requires local, unprivileged shell access to an affected FreeBSD host and the ability to invoke procctl(2) before execve(2) - the concrete prerequisite is calling PROC_ASLR_CTL to request ASLR disable, then executing a target that is BOTH setuid AND built as a position-independent executable (PIE). The flaw is only useful in practice when chained with a separate memory-corruption vulnerability in that setuid binary; on its own it grants no code execution or privilege gain. Limiting factors: it is not remotely exploitable (AV:L), it depends on the presence of a setuid PIE binary that is also separately vulnerable, and it requires the attacker already hold a local account (PR:L), so single-user, non-interactive, or fully patched systems are not at risk. |
| Impact | Signals are consistent and point to a real-but-secondary risk. The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N) correctly reflects an unprivileged local user with no user interaction, and the 7.8 base score is driven by C:H/I:H/A:H - but those high impacts represent the downstream RCE that becomes possible, not a direct effect of this flaw, which by itself only removes a defense-in-depth mitigation and grants no code execution. EPSS is low (0.18%, 8th percentile), there is no CISA KEV listing, and no public exploit identified at time of analysis, all of which align: this is a useful exploitation primitive, not a standalone weaponizable bug. The practical priority is moderate - it elevates the severity of any other memory-corruption vulnerability in a setuid binary, so it should be patched on multi-user FreeBSD hosts, but it does not warrant emergency response on single-user or hardened deployments. Note the discrepancy to weigh: the headline 7.8/H-H-H impact assumes a chained second vulnerability, so treating this in isolation as a full RCE would overstate its standalone danger. |
| Exploit ScenarioDerived | An unprivileged user with shell access on a multi-user FreeBSD server who has discovered (or is chaining) a memory-corruption bug in a local setuid root binary calls procctl(2) to disable ASLR, then execve(2)s the setuid binary, which now loads at a predictable base address. With randomization removed, the attacker reliably crafts ROP/return-to-libc payloads against the second vulnerability to escalate to root. No public exploit for this specific flaw is identified at time of analysis, and the low attack complexity means the primitive is trivial to invoke once a chaining bug is available. |
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Alert meAnalysisAIv1 – Jun 29, 2026
Local ASLR bypass in the FreeBSD ELF image activator (kernel) lets an unprivileged user neutralize address-space layout randomization for setuid PIE binaries. By calling procctl(2) to request ASLR disablement before execve(2), the per-process disable flag remains active when the PIE base address is computed, because the activator clears the flag too late. This is a mitigation-weakening flaw that materially eases exploitation of any separate memory-corruption bug in those privileged binaries; there is no public exploit identified at time of analysis and EPSS is low (0.18%, 8th percentile).
RemediationAI
Apply the FreeBSD security patches to a fixed level: update to FreeBSD 14.3-RELEASE-p15, 14.4-RELEASE-p6, or 15.0-RELEASE-p10 (or later) as documented in advisory FreeBSD-SA-26:32.elf (https://security.freebsd.org/advisories/FreeBSD-SA-26:32.elf.asc), typically via freebsd-update fetch install followed by a reboot. Until patching is possible, the most direct compensating control is to reduce the setuid attack surface - audit and remove or disable the setuid bit on non-essential setuid PIE binaries (chmod u-s), accepting that this can break functionality such as ping, su, or passwd for ordinary users and should be tested per binary. Restricting local/interactive access to trusted users also limits exposure since exploitation requires local code execution, but this only narrows the audience rather than closing the flaw. Generic ASLR sysctl tuning is not a reliable mitigation here because the defect specifically reintroduces a user-controlled disable for privileged targets, so patching is strongly preferred over workarounds.
Affected VersionsENISA
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Technical ContextAI · show details
The issue lives in FreeBSD's kernel ELF image activator, the code path that loads ELF executables during execve(2) and lays out their memory, including the randomized base for position-independent executables (PIE). FreeBSD exposes per-process ASLR control via procctl(2) (PROC_ASLR_CTL), allowing a process to request that randomization be disabled. The bug is a classic CWE-179 (incorrect behavior order / improper handling of case sensitivity-adjacent ordering): for setuid binaries the activator was supposed to discard a user-requested ASLR-disable preference, but it cleared those flags after the base address was already computed instead of before. Because setuid execution crosses a privilege boundary, the user's earlier ASLR-disable request should not carry into the more-privileged process - here it does, defeating ASLR specifically for privileged setuid PIE targets.
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Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local unprivileged trigger (AV:L/AC:L/PR:L) with no direct code execution; the flaw only weakens an integrity mitigation (I:L), so no C/A impact standalone, unlike the vendor's chained 7.8.
Primary rating from Vendor (freebsd).
CVSS VectorVendor: freebsd
Lifecycle Timeline
2DescriptionCVE.org
The ELF image activator cleared per-process ASLR preference flags for setuid binaries after the code that computes the PIE base address, rather than before. As a result, a user-requested ASLR disable was still in effect at the point where the base address was chosen.
An unprivileged local user can disable ASLR for a setuid PIE binary by calling procctl(2) before execve(2). This makes exploitation of any separate memory corruption vulnerability in that binary significantly easier.
Executive ViewAI
A local privilege-escalation weakness in FreeBSD's kernel allows any system user to disable address-space layout randomization (ASLR) on privileged binaries, weakening a critical security defense. The vulnerability requires local system access and no public exploits have been identified, but affected organizations should prioritize disabling unnecessary local access and pre-positioning for emergency patching.
No vendor-released patch identified at time of analysis. Interim mitigations: restrict local user shell access where operationally feasible; apply FreeBSD kernel hardening parameters; disable setuid bits on non-essential privileged binaries; implement application-level exploit detection or address-space entropy monitoring if available; isolate critical services on dedicated single-user systems.
Threat Intelligence Overview
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
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EUVD-2026-39966
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