CVE-2025-39967

Local privilege escalation via font-size integer overflow

Published Oct 15, 2025 · Updated Oct 15, 2025

Integer overflow in Linux kernel fbcon allows local users to corrupt kernel memory through a virtual-console font-setting ioctl. In fbcon_do_set_font, unchecked height, pitch, and character-count multiplication and an extra-word addition can wrap, producing an undersized allocation before font data is copied. An ordinary user controlling a virtual terminal can reach the ioctl without an additional user action, enabling kernel-memory disclosure or modification and a system panic.

CVSS severity7.8
High
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in Linux kernel fbcon allows local users to corrupt kernel memory through a virtual-console font-setting ioctl. In fbcon_do_set_font, unchecked height, pitch, and character-count multiplication and an extra-word addition can wrap, producing an undersized allocation before font data is copied. An ordinary user controlling a virtual terminal can reach the ioctl without an additional user action, enabling kernel-memory disclosure or modification and a system panic.

The record

CVE
CVE-2025-39967
Published
Oct 15, 2025
Updated
Oct 15, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-190, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 15, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 15, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2c455e9c5865861f5ce09c5f596909495ed7657c
  2. Affected versionversion=34cf1aff169dc6dedad8d79da7bf1b4de2773dbc
  3. Affected versionversion=39b3cffb8cf3111738ea993e2757ab382253d86a <1a194e6c8e1ee745e914b0b7f50fa86c89ed13fe
  4. Affected versionversion=39b3cffb8cf3111738ea993e2757ab382253d86a <4a4bac869560f943edbe3c2b032062f6673b13d3
  5. Affected versionversion=39b3cffb8cf3111738ea993e2757ab382253d86a <9c8ec14075c5317edd6b242f1be8167aa1e4e333
  6. Affected versionversion=39b3cffb8cf3111738ea993e2757ab382253d86a <a6eb9f423b3db000aaedf83367b8539f6b72dcfc
  7. Affected versionversion=39b3cffb8cf3111738ea993e2757ab382253d86a <adac90bb1aaf45ca66f9db8ac100be16750ace78
  8. Affected versionversion=39b3cffb8cf3111738ea993e2757ab382253d86a <b8a6e85328aeb9881531dbe89bcd2637a06c3c95
  9. Affected versionversion=39b3cffb8cf3111738ea993e2757ab382253d86a <c0c01f9aa08c8e10e10e8c9ebb5be01a4eff6eb7
  10. Affected versionversion=451bffa366f2cc0e5314807cb847f31c0226efed
  11. Affected versionversion=5.9
  12. Affected versionversion=72f099805dbc907fbe8fa19bccdc31d3e2ee6e9e
  13. Affected versionversion=96e41fc29e8af5c5085fb8a79cab8d0d00bab86c <994bdc2d23c79087fbf7dcd9544454e8ebcef877
  14. Affected versionversion=ae021a904ac82d9fc81c25329d3c465c5a7d5686

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2c455e9c5865861f5ce09c5f596909495ed7657c; version=34cf1aff169dc6dedad8d79da7bf1b4de2773dbc; version=39b3cffb8cf3111738ea993e2757ab382253d86a <1a194e6c8e1ee745e914b0b7f50fa86c89ed13fe; version=39b3cffb8cf3111738ea993e2757ab382253d86a <4a4bac869560f943edbe3c2b032062f6673b13d3; version=39b3cffb8cf3111738ea993e2757ab382253d86a <9c8ec14075c5317edd6b242f1be8167aa1e4e333; version=39b3cffb8cf3111738ea993e2757ab382253d86a <a6eb9f423b3db000aaedf83367b8539f6b72dcfc; version=39b3cffb8cf3111738ea993e2757ab382253d86a <adac90bb1aaf45ca66f9db8ac100be16750ace78; version=39b3cffb8cf3111738ea993e2757ab382253d86a <b8a6e85328aeb9881531dbe89bcd2637a06c3c95; version=39b3cffb8cf3111738ea993e2757ab382253d86a <c0c01f9aa08c8e10e10e8c9ebb5be01a4eff6eb7; version=451bffa366f2cc0e5314807cb847f31c0226efed; version=5.9; version=72f099805dbc907fbe8fa19bccdc31d3e2ee6e9e; version=96e41fc29e8af5c5085fb8a79cab8d0d00bab86c <994bdc2d23c79087fbf7dcd9544454e8ebcef877; version=ae021a904ac82d9fc81c25329d3c465c5a7d5686

Published CVSS scores

7.8Linux kernel CVE teamCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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