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CVE Record

CVE-2024-26786: iommufd: Fix iopt_access_list_id overwrite bug

In the Linux kernel, the following vulnerability has been resolved: iommufd: Fix iopt_access_list_id overwrite bug Syzkaller reported the following WARN_ON: WARNING: CPU: 1 PID: 4738 at drivers/iommu/iommufd/io_pagetable.c:1360 Call Trace: iommufd_access_change_ioas+0x2fe/0x4e0 iommufd_access_destroy_object+0x50/0xb0 iommufd_object_remove+0x2a3/0x490 iommufd_object_destroy_user iommufd_access_destroy+0x71/0xb0 iommufd_test_staccess_release+0x89/0xd0 __fput+0x272/0xb50 __fput_sync+0x4b/0x60 __do_sys_close __se_sys_close __x64_sys_close+0x8b/0x110 do_syscall_x64 The mismatch between the access pointer in the list and the passed-in pointer is resulting from an overwrite of access->iopt_access_list_id, in iopt_add_access(). Called from iommufd_access_change_ioas() when xa_alloc() succeeds but iopt_calculate_iova_alignment() fails. Add a new_id in iopt_add_access() and only update iopt_access_list_id when returning successfully.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux kernel iommufd bookkeeping bug can leave an access object with the wrong list identifier after an error. A locally authenticated, low-privileged user may be able to trigger the vulnerable path without user interaction. The supplied rating indicates potentially serious confidentiality, integrity, and availability impact, although the sources only document a kernel warning and inconsistent state, not a demonstrated compromise.

Executive priority

Treat as a high-priority kernel maintenance issue on systems granting local access to untrusted users, especially virtualization or device-assignment hosts. Patch through normal emergency or accelerated change controls after confirming vendor applicability. Internet-facing status alone does not establish exposure because the stated attack vector is local.

Technical view

In iopt_add_access(), xa_alloc() can succeed before iopt_calculate_iova_alignment() fails, prematurely overwriting access->iopt_access_list_id. Later destruction encounters a mismatch between the stored list pointer and supplied access pointer, producing a WARN_ON. The fix stores the allocated identifier in new_id and updates iopt_access_list_id only after successful completion. The record associates this issue with CWE-476.

Likely exposure

Exposure is limited to Linux systems containing the affected iommufd code and permitting a local low-privileged user to reach it. The bundle names kernel 6.6, 6.6.21, 6.7.9, and 6.8, but does not preserve clear range boundaries. Confirm exact affected and fixed builds through distribution or kernel vendor guidance.

Exploitation context

The CVSS vector describes local access, low complexity, low privileges, and no user interaction. CISA KEV status is false, and the supplied sources provide no evidence of active exploitation or a public exploit. Syzkaller discovered the condition through automated kernel testing. Real-world exploitability and practical security impact are not established in this bundle.

Researcher notes

The failure sequence is specific: xa_alloc() succeeds, alignment calculation fails, and the access identifier has already changed. Cleanup later detects inconsistent list membership. The corrective pattern is transactional assignment of new_id only on success. The bundle does not establish memory corruption, privilege escalation, data disclosure, denial of service, or exploit reliability beyond the CVSS impact assessment.

Mitigation direction

  • Update to a vendor-supported kernel containing the referenced upstream or stable fix.
  • Check distribution advisories for backported fixes because package versions may not match upstream kernel versions.
  • Prioritize multi-user, shared-hosting, and other systems where untrusted users receive local access.
  • Restrict unnecessary local access while awaiting an approved kernel update.

Validation and detection

  • Inventory running kernel versions and identify systems using or exposing iommufd functionality.
  • Map each distribution kernel package to its vendor advisory and backport status.
  • Verify the deployed kernel contains the applicable referenced fix commit or vendor equivalent.
  • After updating, confirm systems boot normally and relevant virtualization or device-assignment workflows pass regression testing.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-476: Exact CWE lookup

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cve · low confidence lookup

CVE-2024-26786 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
3Timeline events
2ADP providers
4Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux
5.5CVSS 3.1MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2024-26786Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux9227da7816dd1a42e20d41e2244cb63c205477ca, 9227da7816dd1a42e20d41e2244cb63c205477ca, 9227da7816dd1a42e20d41e2244cb63c205477caunaffected
LinuxLinux6.6, 0, 6.6.21, 6.7.9, 6.8affected
Weakness

CWE details

CWE-476

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.