VulnerabilityPublished 19 Jul 2026Updated 6 Nov 2026

CVE-2026-64186: Linux kernel · iommu/amd: Remove latent out-of-bounds access in IOMMU debugfs

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in 488d2c76bd9f78433a70690d1054bfae3d39a407 : update Linux kernel when convenient.

Data as of 6 Nov 2026, 17:03 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-06.

Patch

Available – fixed in 488d2c76bd9f78433a70690d1054bfae3d39a407, 62f9dfbf1aceae88b03c5ca08f7d36e943939dec, 8dfd3d8d74435344ee8dc9237596959c8b2a6cbe

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to 488d2c76bd9f78433a70690d1054bfae3d39a407, 62f9dfbf1aceae88b03c5ca08f7d36e943939dec or 8dfd3d8d74435344ee8dc9237596959c8b2a6cbe.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 7a4ee419e8c144b747a8915856e91a034d7c8f34, < 488d2c76bd9f78433a70690d1054bfae3d39a407	Fixed in 488d2c76bd9f78433a70690d1054bfae3d39a407
LinuxLinux	Affected ≥ 7a4ee419e8c144b747a8915856e91a034d7c8f34, < 62f9dfbf1aceae88b03c5ca08f7d36e943939dec	Fixed in 62f9dfbf1aceae88b03c5ca08f7d36e943939dec
LinuxLinux	Affected ≥ 7a4ee419e8c144b747a8915856e91a034d7c8f34, < 8dfd3d8d74435344ee8dc9237596959c8b2a6cbe	Fixed in 8dfd3d8d74435344ee8dc9237596959c8b2a6cbe
LinuxLinux	Affected =6.17	Fixed in–

AI-suggested

A patch is available and has been applied in the Linux kernel to fix this issue by correcting input parsing and adding explicit boundary checks. Users and administrators should update to the fixed kernel versions identified by the commits 488d2c76bd9f78433a70690d1054bfae3d39a407, 62f9dfbf1aceae88b03c5ca08f7d36e943939dec, and 8dfd3d8d74435344ee8dc9237596959c8b2a6cbe. Since this is a kernel vulnerability, applying the official kernel update is the recommended remediation.

Description

CVE-2026-64186 is a vulnerability in the Linux kernel's AMD IOMMU debugfs interface where out-of-bounds memory access could occur due to improper handling of user input values. The flaw arises because integer variables used to store user input offsets were declared as signed integers but populated from unsigned input without proper validation, potentially allowing negative values leading to out-of-bounds access. This issue has been fixed by changing the input parsing function to correctly handle signed integers and explicitly checking for negative values to prevent invalid memory access.

Impact

The vulnerability could allow a user with access to the AMD IOMMU debugfs interface to cause out-of-bounds memory access, which may lead to undefined behavior or potential security risks such as information disclosure or system instability. However, prior protections limited the input size and range, reducing the likelihood of exploitation. No known exploits in the wild have been reported.

Summary

The vulnerability in the Linux kernel's AMD IOMMU debugfs implementation involves latent out-of-bounds access caused by improper parsing of user-supplied offset values in iommu_mmio_write() and iommu_capability_write(). Variables dbg_mmio_offset and dbg_cap_offset were declared as int but populated using kstrtou32_from_user(), which parses unsigned 32-bit integers. If a user provides a sufficiently large value, it can wrap around to a negative integer, potentially causing out-of-bounds memory access. The fix replaces kstrtou32_from_user() with kstrtos32_from_user() to parse signed integers and adds explicit checks for negative values, preventing such invalid accesses. Additional existing protections include input size limits and range checks, but this patch directly addresses the root cause.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 6 Nov 2026, 17:03 UTC

Technical details

References

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