fbdev: fbcon: fix out-of-bounds read in err_out of fbcon_do_set_font()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-53402
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-19 12:16:51 UTC
Updated2026-07-20 15:16:42 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.001680000 probability, percentile 0.065100000 (date 2026-07-20)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.1HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
3.1CNADECLARED7.1HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 b5bb2c696e140c399cb874def2feedf61dee27d6 git Not specified
CNA Linux Linux affected a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 076b1aa65f77a49bce5a48a4a55a397cfcafa2b8 git Not specified
CNA Linux Linux affected a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 39815715cbcfabb16fc8c5f4a23deeda20f5df62 git Not specified
CNA Linux Linux affected a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 8fdc8c2057eea08d40ce2c8eed41ff9e451c65c2 git Not specified
CNA Linux Linux affected 868749a7456dc48e93887a8474194e2ee6d6c21f git Not specified
CNA Linux Linux affected ebd6f886aa2447fcfcdce5450c9e1028e1d681bb git Not specified
CNA Linux Linux affected f08ccb792d3eaf1dc62d8cbf6a30d6522329f660 git Not specified
CNA Linux Linux affected 5.10.249 5.11 semver Not specified
CNA Linux Linux affected 5.15.64 5.16 semver Not specified
CNA Linux Linux affected 5.19.6 5.20 semver Not specified
CNA Linux Linux affected 6.0 Not specified
CNA Linux Linux unaffected 6.0 semver Not specified
CNA Linux Linux unaffected 6.12.96 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.39 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.3 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/b5bb2c696e140c399cb874def2feedf61dee27d6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8fdc8c2057eea08d40ce2c8eed41ff9e451c65c2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/076b1aa65f77a49bce5a48a4a55a397cfcafa2b8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/39815715cbcfabb16fc8c5f4a23deeda20f5df62 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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