EUVD-2026-64529
GHSA-hgmq-24pq-jx89
Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
AV:L because file truncation is a local syscall; AC:H because non-default IMA appraisal policy must be configured and attacker needs truncate rights on a policy-covered file.
Primary rating from Vendor (Linux).
CVSS VectorVendor: Linux
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Lifecycle Timeline
5DescriptionCVE.org
In the Linux kernel, the following vulnerability has been resolved:
ima: Instantiate file_truncate and path_truncate hooks
Instantiate the file_truncate and path_truncate LSM hooks to reset the action cache flags (IMA_DONE_MASK) as soon as truncation is requested, so the file, based on policy, is re-collected, re-measured, re-audited, and re-appraised on next access.
AnalysisAI
The IMA (Integrity Measurement Architecture) subsystem in the Linux kernel fails to invalidate action cache flags (IMA_DONE_MASK) when files are truncated, because the file_truncate and path_truncate LSM hooks were not instantiated in IMA's hook logic. Authenticated local users who can truncate a file covered by an active IMA policy can exploit this gap - causing the kernel to skip re-measurement, re-auditing, and re-appraisal on the next file access, effectively bypassing IMA integrity enforcement for that file. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the Linux kernel IMA subsystem to be enabled AND configured with active appraisal or measurement policies - this is a non-default configuration not present in standard Linux distribution deployments out of the box. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The assigned CVSS 8.1 score with AV:N (network attack vector) warrants independent verification - file truncation is a local filesystem syscall operation, and the network vector is difficult to reconcile with the described attack mechanism unless network-mounted filesystems (NFS, CIFS) with appropriate permissions are assumed; this discrepancy should be confirmed against the official NVD record. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker with low-privilege authenticated local access on a Linux system running IMA appraisal policies identifies an IMA-monitored executable or configuration file on which they hold write and truncate permissions. The attacker invokes the truncate syscall on the file, zeroing its content while leaving IMA's IMA_DONE_MASK cache flags in the 'already appraised' state; on the next access, IMA skips re-appraisal of the now-empty file. … |
| Remediation | Upgrade to a patched Linux kernel version appropriate for your current stable branch: 6.12.104, 6.18.45, 7.1.9, or 7.2. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: identify all systems running Linux with IMA policies enabled by checking kernel parameters (ima_policy=) and audit logs. …
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External POC / Exploit Code
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