CyberSecBulletin
CVE-2026-53402NVD status: Modified

Linux: Out-of-bounds Read

Published Updated By the CyberSecBulletin desk

CVE-2026-53402 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions cb016bcb40c81e7b19c4ae6143babb366dae8e20, ac562193c36696513ae196171892e9338475c4bc, 3618a4c5b2591cfa83efe74f5b18c2d02b35c3f5 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.17% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to cb016bcb40c81e7b19c4ae6143babb366dae8e20 or ac562193c36696513ae196171892e9338475c4bc or 3618a4c5b2591cfa83efe74f5b18c2d02b35c3f5 or a7a526fbc847f07ad3a503c7382189be5ab68574, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.261 or 5.15.212 or 6.0 or 6.1.178, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux868749a7456dc48e93887a8474194e2ee6d6c21f up to, but not including, cb016bcb40c81e7b19c4ae6143babb366dae8e20; ebd6f886aa2447fcfcdce5450c9e1028e1d681bb up to, but not including, ac562193c36696513ae196171892e9338475c4bc; a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 up to, but not including, 3618a4c5b2591cfa83efe74f5b18c2d02b35c3f5; a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 up to, but not including, a7a526fbc847f07ad3a503c7382189be5ab68574; a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 up to, but not including, b5bb2c696e140c399cb874def2feedf61dee27d6; a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 up to, but not including, 076b1aa65f77a49bce5a48a4a55a397cfcafa2b8; a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 up to, but not including, 39815715cbcfabb16fc8c5f4a23deeda20f5df62; a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 up to, but not including, 8fdc8c2057eea08d40ce2c8eed41ff9e451c65c2; and 5 more rangescb016bcb40c81e7b19c4ae6143babb366dae8e20, ac562193c36696513ae196171892e9338475c4bc, 3618a4c5b2591cfa83efe74f5b18c2d02b35c3f5, a7a526fbc847f07ad3a503c7382189be5ab68574, b5bb2c696e140c399cb874def2feedf61dee27d6, 076b1aa65f77a49bce5a48a4a55a397cfcafa2b8
LinuxLinux Kernel5.10.249 up to, but not including, 5.10.261; 5.15.64 up to, but not including, 5.15.212; 5.19.6 up to, but not including, 6.0; 6.0.1 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.145; 6.7 up to, but not including, 6.12.96; 6.13 up to, but not including, 6.18.39; 6.19 up to, but not including, 7.1.3; and 1 more ranges5.10.261, 5.15.212, 6.0, 6.1.178, 6.6.145, 6.12.96

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: fbdev: fbcon: fix out-of-bounds read in err_out of fbcon_do_set_font() When fbcon_do_set_font() fails (e.g., due to a memory allocation failure inside vc_resize() under heavy memory pressure), it jumps to the `err_out` label to roll back the console state. However, the current rollback logic forgets to restore the `hi_font` state, leading to a severe state machine corruption. Earlier in the function, `set_vc_hi_font()` might be called to change `vc->vc_hi_font_mask` and mutate the screen buffer. If `vc_resize()` subsequently fails, the `err_out` path restores `vc_font.charcount` but entirely skips rolling back the `vc_hi_font_mask` and the screen buffer. This mismatch leaves the terminal in a desynchronized state. Because `vc_hi_font_mask` remains set, the VT subsystem will still accept character indices greater than 255 from userspace and write them to the screen buffer. Subsequent rendering calls (e.g., `fbcon_putcs()`) will then use these inflated indices to access the reverted, 256-character font array, leading to a deterministic out-of-bounds read and potential kernel memory disclosure. Fix this by adding the missing rollback logic for the `hi_font` mask and screen buffer in the error path.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Read

The product reads data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that provides appropriate memory abstractions.

More Out-of-bounds Read vulnerabilities (CWE-125)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Read vulnerabilities

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