CVE-2026-53402 (GCVE-0-2026-53402)

Vulnerability from cvelistv5 – Published: 2026-07-19 12:02 – Updated: 2026-07-20 13:40
VLAI
Title
fbdev: fbcon: fix out-of-bounds read in err_out of fbcon_do_set_font()
Summary
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.
Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 , < b5bb2c696e140c399cb874def2feedf61dee27d6 (git)
Affected: a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 , < 076b1aa65f77a49bce5a48a4a55a397cfcafa2b8 (git)
Affected: a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 , < 39815715cbcfabb16fc8c5f4a23deeda20f5df62 (git)
Affected: a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 , < 8fdc8c2057eea08d40ce2c8eed41ff9e451c65c2 (git)
Affected: 868749a7456dc48e93887a8474194e2ee6d6c21f (git)
Affected: ebd6f886aa2447fcfcdce5450c9e1028e1d681bb (git)
Affected: f08ccb792d3eaf1dc62d8cbf6a30d6522329f660 (git)
Affected: 5.10.249 , < 5.11 (semver)
Affected: 5.15.64 , < 5.16 (semver)
Affected: 5.19.6 , < 5.20 (semver)
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Linux Linux Affected: 6.0
Unaffected: 0 , < 6.0 (semver)
Unaffected: 6.12.96 , ≤ 6.12.* (semver)
Unaffected: 6.18.39 , ≤ 6.18.* (semver)
Unaffected: 7.1.3 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)
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If `vc_resize()`\\nsubsequently fails, the `err_out` path restores `vc_font.charcount`\\nbut entirely skips rolling back the `vc_hi_font_mask` and the screen\\nbuffer.\\n\\nThis mismatch leaves the terminal in a desynchronized state. Because\\n`vc_hi_font_mask` remains set, the VT subsystem will still accept\\ncharacter indices greater than 255 from userspace and write them to the\\nscreen buffer. Subsequent rendering calls (e.g., `fbcon_putcs()`) will\\nthen use these inflated indices to access the reverted, 256-character\\nfont array, leading to a deterministic out-of-bounds read and potential\\nkernel memory disclosure.\\n\\nFix this by adding the missing rollback logic for the `hi_font` mask\\nand screen buffer in the error path.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/video/fbdev/core/fbcon.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24\",\"lessThan\":\"b5bb2c696e140c399cb874def2feedf61dee27d6\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24\",\"lessThan\":\"076b1aa65f77a49bce5a48a4a55a397cfcafa2b8\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24\",\"lessThan\":\"39815715cbcfabb16fc8c5f4a23deeda20f5df62\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24\",\"lessThan\":\"8fdc8c2057eea08d40ce2c8eed41ff9e451c65c2\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"868749a7456dc48e93887a8474194e2ee6d6c21f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"ebd6f886aa2447fcfcdce5450c9e1028e1d681bb\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"f08ccb792d3eaf1dc62d8cbf6a30d6522329f660\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"5.10.249\",\"lessThan\":\"5.11\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"5.15.64\",\"lessThan\":\"5.16\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"5.19.6\",\"lessThan\":\"5.20\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/video/fbdev/core/fbcon.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.0\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.0\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.96\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.39\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.3\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H\",\"baseScore\":7.1,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.2}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/076b1aa65f77a49bce5a48a4a55a397cfcafa2b8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/39815715cbcfabb16fc8c5f4a23deeda20f5df62\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8fdc8c2057eea08d40ce2c8eed41ff9e451c65c2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b5bb2c696e140c399cb874def2feedf61dee27d6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-20T15:44:48+00:00",
      "cve": "CVE-2026-53402",
      "id": "CVE-2026-53402",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: fbdev: fbcon: fix out-of-bounds read in err_out of fbcon_do_set_font()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53402.json",
      "version": "3"
    }
  }
}



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Sightings

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
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