EUVD-2026-39887
GHSA-865v-r97p-c9pq
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Invoking kexec_load requires CAP_SYS_BOOT (root), justifying PR:H over the provided PR:L; impact is pure availability disruption with no C or I.
Primary rating from NVD.
CVSS VectorNVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
5DescriptionNVD
In the Linux kernel, the following vulnerability has been resolved:
x86/kexec: Push kjump return address even for non-kjump kexec
The version of purgatory code shipped by kexec-tools attempts to look above the top of its stack to find a return address for a kjump, even in a non-kjump kexec.
After the commit in Fixes: the word above the stack might not be there, leading to a fault (which is at least now caught by my exception-handling code in kexec).
That commit fixed things for the actual kjump path, but no longer "gratuitously" pushes the unused return address to the stack in the non-kjump path. Put that *back* in the non-kjump path, to prevent purgatory from crashing when trying to access it.
AnalysisAI
Stack access fault in the x86/kexec purgatory handoff crashes non-kjump kexec operations on affected Linux kernel versions, resulting in a local denial of service. A prior regression removed a 'gratuitous' stack push in the non-kjump path; however, the purgatory code shipped by kexec-tools still reads above its stack top expecting that return address, triggering a memory fault that aborts the kexec reboot or crashes the system. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires local access and CAP_SYS_BOOT (root-equivalent) to invoke the kexec_load system call. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The provided CVSS 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) captures the local, availability-only nature of the flaw accurately, though PR:L likely underestimates the privilege bar - invoking kexec_load typically requires CAP_SYS_BOOT, effectively root, which aligns better with PR:H. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A system administrator or privileged local process invokes kexec to reboot into a new kernel using the standard non-kjump path. During the handoff, the kexec-tools purgatory code reads one word above its own stack top expecting a kjump return address that the kernel no longer pushes. … |
| Remediation | Upgrade to a fixed kernel version: Linux 7.1, 7.0.10, or 6.18.33, all of which restore the missing stack push in the non-kjump kexec path. … Detailed patch versions, workarounds, and compensating controls in full report. |
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Same technique Denial Of Service
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External POC / Exploit Code
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