Bug 2419902 (CVE-2025-40322)

Summary:	CVE-2025-40322 kernel: Linux kernel: Information disclosure and denial of service via out-of-bounds read in font glyph handling
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	ctejagigamon, heikki.pora, prodsec-dev
Target Milestone:	---	Keywords:	Security
Target Release:	---	Flags:	ctejagigamon: needinfo? (prodsec-dev) heikki.pora: needinfo-
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel. A local attacker can exploit this vulnerability by providing a specially crafted font glyph index to the bitblit component. This can lead to an out-of-bounds read, potentially resulting in information disclosure or a denial of service.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2025-12-08 07:07:25 UTC

In the Linux kernel, the following vulnerability has been resolved:

fbdev: bitblit: bound-check glyph index in bit_putcs*

bit_putcs_aligned()/unaligned() derived the glyph pointer from the
character value masked by 0xff/0x1ff, which may exceed the actual font's
glyph count and read past the end of the built-in font array.
Clamp the index to the actual glyph count before computing the address.

This fixes a global out-of-bounds read reported by syzbot.

Comment 1 Jon Moroney 2025-12-08 21:09:56 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025120823-CVE-2025-40322-6355@gregkh/T

Comment 3 errata-xmlrpc 2026-02-02 03:21:57 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:1661 https://access.redhat.com/errata/RHSA-2026:1661

Comment 4 errata-xmlrpc 2026-02-02 03:53:33 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:1662 https://access.redhat.com/errata/RHSA-2026:1662

Comment 5 errata-xmlrpc 2026-02-02 15:25:26 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:1727 https://access.redhat.com/errata/RHSA-2026:1727

Comment 9 errata-xmlrpc 2026-02-09 09:32:01 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:2282 https://access.redhat.com/errata/RHSA-2026:2282

Comment 10 Heikki Pora 2026-02-09 11:50:32 UTC

The fix is faulty in that it expects vc->vc_font.charcount to be always set.
See https://lkml.org/lkml/2026/1/5/540 for an explanation and a fix.

The issue applies to RHEL v8.10 kernel at least, causing garbage text display (only white blocks) on fbcon virtual consoles as described by the author of the referenced lkml post.

Comment 11 errata-xmlrpc 2026-02-09 17:46:41 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:2352 https://access.redhat.com/errata/RHSA-2026:2352

Comment 12 errata-xmlrpc 2026-02-11 00:16:06 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.6 Telecommunications Update Service

Via RHSA-2026:2490 https://access.redhat.com/errata/RHSA-2026:2490

Comment 13 errata-xmlrpc 2026-02-11 11:51:00 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.8 Telecommunications Update Service

Via RHSA-2026:2535 https://access.redhat.com/errata/RHSA-2026:2535

Comment 14 errata-xmlrpc 2026-02-11 14:34:07 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:2560 https://access.redhat.com/errata/RHSA-2026:2560

Comment 15 errata-xmlrpc 2026-02-11 16:30:40 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions

Via RHSA-2026:2573 https://access.redhat.com/errata/RHSA-2026:2573

Comment 16 errata-xmlrpc 2026-02-11 17:04:15 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions

Via RHSA-2026:2577 https://access.redhat.com/errata/RHSA-2026:2577

Comment 17 errata-xmlrpc 2026-02-11 17:45:04 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:2583 https://access.redhat.com/errata/RHSA-2026:2583

Comment 18 errata-xmlrpc 2026-02-12 00:44:47 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Extended Update Support

Via RHSA-2026:2594 https://access.redhat.com/errata/RHSA-2026:2594

Comment 19 errata-xmlrpc 2026-02-12 15:12:35 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.2 Advanced Update Support

Via RHSA-2026:2664 https://access.redhat.com/errata/RHSA-2026:2664

Comment 20 errata-xmlrpc 2026-02-16 12:02:47 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:2722 https://access.redhat.com/errata/RHSA-2026:2722

Comment 21 Chandra Teja 2026-02-21 18:35:29 UTC

Can anyone share update on causing garbage text display (only white blocks) with Latest redhat kernels after this fix ?

I couldn't find any CVE references showing the issue with Latest kernel ( 4.18.0-553.104.1 ) which gives white blocks instead of clear text while booting.

Thanks.

Comment 22 errata-xmlrpc 2026-02-25 15:16:43 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

Via RHSA-2026:3360 https://access.redhat.com/errata/RHSA-2026:3360