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NVD / CVE Program· CNA Linux

CVE-2024-26798: fbcon: always restore the old font data in fbcon_do_set_font()

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.32% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 00d6a284fcf3fad1b7e1b5bc3cd87cbfb60ce03f, 20a4b5214f7bee13c897477168c77bbf79683c3d, 2f91a96b892fab2f2543b4a55740c5bee36b1a6b.
  • Mentioned 2 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 00d6a284fcf3fad1b7e1b5bc3cd87cbfb60ce03f, 20a4b5214f7bee13c897477168c77bbf79683c3d, 2f91a96b892fab2f2543b4a55740c5bee36b1a6b or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: fbcon: always restore the old font data in fbcon_do_set_font() Commit a5a923038d70 (fbdev: fbcon: Properly revert changes when vc_resize() failed) started restoring old font data upon failure (of vc_resize()). But it performs so only for user fonts. It means that the "system"/internal fonts are not restored at all. So in result, the very first call to fbcon_do_set_font() performs no restore at all upon failing vc_resize(). This can be reproduced by Syzkaller to crash the system on the next invocation of font_get(). It's rather hard to hit the allocation failure in vc_resize() on the first font_set(), but not impossible. Esp. if fault injection is used to aid the execution/failure. It was demonstrated by Sirius: BUG: unable to handle page fault for address: fffffffffffffff8 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD cb7b067 P4D cb7b067 PUD cb7d067 PMD 0 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 8007 Comm: poc Not tainted 6.7.0-g9d1694dc91ce #20 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:fbcon_get_font+0x229/0x800 drivers/video/fbdev/core/fbcon.c:2286 Call Trace: <TASK> con_font_get drivers/tty/vt/vt.c:4558 [inline] con_font_op+0x1fc/0xf20 drivers/tty/vt/vt.c:4673 vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline] vt_ioctl+0x632/0x2ec0 drivers/tty/vt/vt_ioctl.c:752 tty_ioctl+0x6f8/0x1570 drivers/tty/tty_io.c:2803 vfs_ioctl fs/ioctl.c:51 [inline] ... So restore the font data in any case, not only for user fonts. Note the later 'if' is now protected by 'old_userfont' and not 'old_data' as the latter is always set now. (And it is supposed to be non-NULL. Otherwise we would see the bug above again.)

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Apr 4, 2024
Updated
Jun 17, 2026
EPSS
0.3% · 25th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2024-26798

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.15.64 and later · before 5.15.151
  • linux linux kernel6.0 and later · before 6.1.81
  • linux linux kernel6.2 and later · before 6.6.21
  • linux linux kernel6.7 and later · before 6.7.9
  • linux linux kernel6.8

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • f08ccb792d3eaf1dc62d8cbf6a30d6522329f660, 6.0affected
    • 868749a7456dc48e93887a8474194e2ee6d6c21f and later · before ae68f57df3335679653868fafccd8c88ef84ae98affected · git
    • ebd6f886aa2447fcfcdce5450c9e1028e1d681bb and later · before 20a4b5214f7bee13c897477168c77bbf79683c3daffected · git
    • a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 and later · before 2f91a96b892fab2f2543b4a55740c5bee36b1a6baffected · git
    • a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 and later · before 73a6bd68a1342f3a44cac9dffad81ad6a003e520affected · git
    • a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 and later · before a2c881413dcc5d801bdc9535e51270cc88cb9cd8affected · git
    • a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 and later · before 00d6a284fcf3fad1b7e1b5bc3cd87cbfb60ce03faffected · git
    • 5.15.64 and later · before 5.15.151affected · semver
    • 5.19.6 and later · before 5.20affected · semver
    • before 6.0not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.82-16.1.82-1
Debian:13linuxbefore 6.7.9-16.7.9-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2024-26796Apr 4, 2024 · drivers: perf: ctr_get_width function for legacy is not defined
    22Monitor
  • ← EarlierCVE-2024-26797Apr 4, 2024 · drm/amd/display: Prevent potential buffer overflow in map_hw_resources
    31Monitor
  • Later →CVE-2024-26800Apr 4, 2024 · tls: fix use-after-free on failed backlog decryption
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux00d6a284fcf3fad1b7e1b5bc3cd87cbfb60ce03fVendor (CNA)
Linux Linux20a4b5214f7bee13c897477168c77bbf79683c3dVendor (CNA)
Linux Linux2f91a96b892fab2f2543b4a55740c5bee36b1a6bVendor (CNA)
Linux Linux5.15.151Vendor (CNA)
Linux Linux5.20Vendor (CNA)
Linux Linux73a6bd68a1342f3a44cac9dffad81ad6a003e520Vendor (CNA)
Linux Linuxa2c881413dcc5d801bdc9535e51270cc88cb9cd8Vendor (CNA)
Linux Linuxae68f57df3335679653868fafccd8c88ef84ae98Vendor (CNA)
debian:linux6.1.82-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2021-4713710 days apartnet: lantiq: fix memory corruption in RX ring
    39Monitor
  • CVE-2024-3596946 days apartipv6: fix race condition between ipv6_get_ifaddr and ipv6_del_addr
    35Monitor
  • CVE-2021-4755150 days apartdrm/amd/amdkfd: Fix kernel panic when reset failed and been triggered again
    31Monitor
  • CVE-2024-3402781 days apartf2fs: compress: fix to cover {reserve,release}_compress_blocks() w/ cp_rwsem lock
    31Monitor
  • CVE-2021-4713020 days apartnvmet: fix freeing unallocated p2pmem
    30Monitor
  • CVE-2024-2689413 days apartACPI: processor_idle: Fix memory leak in acpi_processor_power_exit()
    24Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-770 · Allocation of Resources Without Limits or Throttling

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records