[CVE-2026-64546][MODERATE REGULAR] drm/edid: fix OOB read in drm_parse_tiled_block() [ Upstream

[CVE-2026-64546][MODERATE REGULAR] drm/edid: fix OOB read in drm_parse_tiled_block() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64546
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/edid: fix OOB read in drm_parse_tiled_block() [ Upstream
Commit: c4ab04ca1bbf87eefa9fec5c80e1880450d2e7c0
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c4ab04ca1bbf87eefa9fec5c80e1880450d2e7c0
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64546
Analysis date: Mon, 27 Jul 2026 22:14:43 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline manual review recommended / ordinary Moderate, not Important
Manual review required: YES

Summary:
A crafted EDID tiled-display block can make drm_parse_tiled_block read past the kmemdup allocated DisplayID buffer, causing a heap out-of-bounds read with limited information disclosure or kernel crash impact through malicious physical or virtual display input.

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ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-64546 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64546

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: MODERATE REGULAR
Manual review required: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-64546	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H';CWE-125;*CWE-20;CWE-754;CWE-125;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L';BEST CVSS score: '5.2';DESCR 'A heap out of bounds read in drm_parse_tiled_block can occur because the DisplayID tiled block is parsed as a fixed layout before checking that block num_bytes contains the required 22 byte payload. A crafted EDID from a malicious monitor adapter display emulator or virtual display device can place a short tiled-display block at the end of a DisplayID extension and make the DRM EDID parser read past the kmemdup allocated EDID buffer. For the CVSS the PR:N is used because the attacker does not need an account or local privileges on the victim when the crafted EDID is supplied by the attached display endpoint. The issue is not network reachable in the normal IP sense and is mainly exposed through physical or virtual display attachment. Impact is at least limited confidentiality risk from an out of bounds heap read and denial of service if the invalid read triggers a kernel crash. No direct integrity impact is indicated because the primitive is read-only and there is no evidence of an out of bounds write.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended / ordinary Moderate, not Important (with actual score 3)	YES	READ KASAN OOB HARDWARE  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Borderline manual review recommended / ordinary Moderate, not Important**::

## 2. Signal breakdown

Triggered signals:

* Firmware-mediated external influence: +1
  The attacker-controlled input is EDID data supplied by a malicious monitor, adapter, display emulator, or virtual display device.

* Confidentiality impact plausible: +1
  The primitive is a heap out-of-bounds read from an exact-sized kmemdup EDID buffer. Limited adjacent heap data exposure is plausible, although no direct user-visible disclosure primitive is shown.

* Reliable kernel crash / strong DoS: +1 in paranoid score only
  KASAN shows a slab-out-of-bounds read in drm_edid_connector_update. In production, a small read past the allocation may not always crash, so this is counted only for the paranoid score.

* Broad/default/common subsystem: +1
  DRM EDID parsing is common on graphical systems and is exercised during connector probing.

Subtracted signals:

* Physical-only or rare hardware-only condition: -2
  The realistic attacker normally needs control over a physically attached or virtualized display endpoint. This is not IP-network reachable.

Not awarded:

* No generic memory corruption +2
  This is read-only OOB, not UAF, double-free, OOB write, heap overwrite, or arbitrary write.

* No privilege escalation plausible +2
  The patch shows a bounded OOB read, not attacker-controlled write, reclaim, type confusion, callback control, or refcount takeover.

* No integrity impact
  No write primitive is present.

Call-site confidence: high. The commit includes the faulting call path through drm_edid_connector_update and the changed parser site.

## 3. Reachability analysis

The bug is triggered when DRM parses a crafted DisplayID tiled-display block with block num_bytes smaller than the required 22-byte tiled payload. The realistic attacker is someone controlling EDID data through a malicious monitor, adapter, display emulator, virtual display device, or test environment. No local account is required if the crafted EDID is supplied by the display endpoint, but physical or virtual display attachment is usually required.

Namespaces and containers generally do not make this broadly reachable unless the container or guest can influence the virtual display EDID or trigger host-side connector probing. The path is common on systems using DRM display probing, but exposure to untrusted EDID is environment-dependent.

## 4. Severity interpretation

This behaves like an ordinary Moderate issue with manual review value, not an Important-class vulnerability. The demonstrated primitive is a heap out-of-bounds read and possible crash, with limited confidentiality concern. Realistic exploitation evidence does not show code execution, LPE, integrity impact, object replacement, or arbitrary memory access.

The paranoid interpretation raises the score to 3 because EDID is attacker-controlled external input and the KASAN trace confirms an invalid heap read in kernel context. It still should not be treated as a strong memory corruption or privilege escalation candidate.

## 5. One-sentence report phrase

A crafted EDID tiled-display block can make drm_parse_tiled_block read past the kmemdup allocated DisplayID buffer, causing a heap out-of-bounds read with limited information disclosure or kernel crash impact through malicious physical or virtual display input.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is externally supplied kernel input and a confirmed heap OOB read, but the primitive is read-only, physical or virtual display mediated, and lacks evidence of LPE or integrity impact.

======================================================================
UPSTREAM PATCH SUMMARY
======================================================================

Patch: drm/edid: fix OOB read in drm_parse_tiled_block() [ Upstream
Commit: c4ab04ca1bbf87eefa9fec5c80e1880450d2e7c0
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c4ab04ca1bbf87eefa9fec5c80e1880450d2e7c0

Changed files:
  lib/dump_stack.c
  mm/kasan/report.c
  drivers/gpu/drm/drm_edid.c
  drivers/gpu/drm/tiny/bochs.c
  drivers/gpu/drm/drm_probe_helper.c
  drivers/gpu/drm/drm_sysfs.c
  fs/read_write.c

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c4ab04ca1bbf87eefa9fec5c80e1880450d2e7c0

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-64546 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64546

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
  The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS score: 5.2

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: 2
  Paranoid ActionableScore: 3

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).