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Fencer Intel
high 7.8

CVE-2021-47383 json

tty: Fix out-of-bound vmalloc access in imageblit

published 2y ago modified 3mo ago also EUVD-2021-34388

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 18%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

tty: Fix out-of-bound vmalloc access in imageblit

This issue happens when a userspace program does an ioctl FBIOPUT_VSCREENINFO passing the fb_var_screeninfo struct containing only the fields xres, yres, and bits_per_pixel with values.

If this struct is the same as the previous ioctl, the vc_resize() detects it and doesn't call the resize_screen(), leaving the fb_var_screeninfo incomplete. And this leads to the updatescrollmode() calculates a wrong value to fbcon_display->vrows, which makes the real_y() return a wrong value of y, and that value, eventually, causes the imageblit to access an out-of-bound address value.

To solve this issue I made the resize_screen() be called even if the screen does not need any resizing, so it will "fix and fill" the fb_var_screeninfo independently.

Patch / fix

  • Linux Linux 4.4.286, 4.9.285, 4.14.249, 4.19.209, 5.4.151, 5.10.71, 5.14.10, 5.15
  • linux Debian 14, Debian 13, Debian 12 5.14.12-1

debian advisories DEBIAN-CVE-2021-47383

  • linux Ubuntu 18.04 LTS 4.15.0-163.171
  • linux Ubuntu 20.04 LTS 5.4.0-91.102
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1116.123
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1060.63
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1058.62
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1008.9
  • linux-kvm Ubuntu 18.04 LTS 4.15.0-1103.105
  • linux-kvm Ubuntu 20.04 LTS 5.4.0-1050.52

ubuntu advisories UBUNTU-CVE-2021-47383

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 9 5.14.0-427.42.1.el9_4
  • rv RHEL 9 5.14.0-427.42.1.el9_4
  • perf RHEL 9 5.14.0-427.42.1.el9_4
  • rtla RHEL 9 5.14.0-427.42.1.el9_4
  • bpftool RHEL 9 7.3.0-427.42.1.el9_4
  • libperf RHEL 9 5.14.0-427.42.1.el9_4
  • kernel-rt RHEL 9 5.14.0-427.42.1.el9_4
  • kernel-64k RHEL 9 5.14.0-427.42.1.el9_4

red hat advisories RHSA-2024:8617RHSA-2024:7000RHSA-2024:7001RHSA-2024:5364RHSA-2024:5365

  • kernel-livepatch-SLE15-SP3_Update_42 SLE Live Patching 15 SP3 12-150300.7.6.1
  • kernel-livepatch-SLE15-SP3_Update_43 SLE Live Patching 15 SP3 11-150300.7.6.1
  • kernel-livepatch-SLE15-SP3_Update_44 SLE Live Patching 15 SP3 10-150300.7.6.1
  • kernel-livepatch-SLE15-SP3_Update_44 SLE Live Patching 15 SP3 9-150300.7.6.1
  • kernel-livepatch-SLE15-SP3_Update_43 SLE Live Patching 15 SP3 10-150300.7.6.1
  • kgraft-patch-SLE12-SP5_Update_54 SLE Live Patching 12 SP5 11-8.10.1
  • kernel-livepatch-SLE15-SP3_Update_42 SLE Live Patching 15 SP3 11-150300.7.6.1
  • kgraft-patch-SLE12-SP5_Update_56 SLE Live Patching 12 SP5 9-8.6.1

suse advisories SUSE-SU-2025:0244-1SUSE-SU-2025:0240-1SUSE-SU-2025:0238-1SUSE-SU-2025:0137-1SUSE-SU-2025:0106-1SUSE-SU-2025:0103-1

  • kernel AlmaLinux 9 5.14.0-427.42.1.el9_4
  • rv AlmaLinux 9 5.14.0-427.42.1.el9_4
  • perf AlmaLinux 9 5.14.0-427.42.1.el9_4
  • rtla AlmaLinux 9 5.14.0-427.42.1.el9_4
  • bpftool AlmaLinux 9 7.3.0-427.42.1.el9_4
  • libperf AlmaLinux 9 5.14.0-427.42.1.el9_4
  • kernel-rt AlmaLinux 9 5.14.0-427.42.1.el9_4
  • kernel-64k AlmaLinux 9 5.14.0-427.42.1.el9_4

almalinux advisories ALSA-2024:8617ALSA-2024:7000ALSA-2024:7001

  • kernel Rocky Linux 8 4.18.0-553.22.1.el8_10
  • kernel Rocky Linux 9 5.14.0-427.42.1.el9_4
  • kernel-rt Rocky Linux 8 4.18.0-553.22.1.rt7.363.el8_10

rocky linux advisories RLSA-2024:7000RLSA-2024:8617RLSA-2024:7001

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-47383 updated cvss 6.6

kernel: tty: Fix out-of-bound vmalloc access in imageblit

  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: workaround, no fix planned “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.”
  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: workaround, no fix available “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.”
  • Red Hat CodeReady Linux Builder EUS (v.9.2) kernel-debuginfo-common-s390x 5.14.0-284.79.1.el9_2, kernel-debuginfo-common-x86_64 5.14.0-284.79.1.el9_2, kernel-debuginfo-common-aarch64 5.14.0-284.79.1.el9_2, kernel-debuginfo-common-ppc64le 5.14.0-284.79.1.el9_2
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:5364
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-427.42.1.el9_4, perf 5.14.0-427.42.1.el9_4, rtla 5.14.0-427.42.1.el9_4, kernel-devel-matched 5.14.0-427.42.1.el9_4, kernel-64k-devel-matched 5.14.0-427.42.1.el9_4, kernel-debug-devel-matched 5.14.0-427.42.1.el9_4, +6 more
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:8617
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) perf 5.14.0-284.79.1.el9_2, rtla 5.14.0-284.79.1.el9_2, kernel-devel-matched 5.14.0-284.79.1.el9_2, kernel-64k-devel-matched 5.14.0-284.79.1.el9_2, kernel-debug-devel-matched 5.14.0-284.79.1.el9_2, kernel-debuginfo-common-s390x 5.14.0-284.79.1.el9_2, +5 more
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:5364
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.22.1.el8_10, kernel 4.18.0-553.22.1.el8_10, bpftool 4.18.0-553.22.1.el8_10, kernel-core 4.18.0-553.22.1.el8_10, kernel-tools 4.18.0-553.22.1.el8_10, python3-perf 4.18.0-553.22.1.el8_10, +15 more
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:7000
  • Red Hat Enterprise Linux BaseOS (v. 9) bpftool 7.3.0-427.42.1.el9_4, kernel 5.14.0-427.42.1.el9_4, kernel-64k 5.14.0-427.42.1.el9_4, kernel-core 5.14.0-427.42.1.el9_4, kernel-tools 5.14.0-427.42.1.el9_4, python3-perf 5.14.0-427.42.1.el9_4, +28 more
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:8617
  • Red Hat Enterprise Linux BaseOS EUS (v.9.2) bpftool 7.0.0-284.79.1.el9_2, kernel 5.14.0-284.79.1.el9_2, kernel-64k 5.14.0-284.79.1.el9_2, kernel-core 5.14.0-284.79.1.el9_2, kernel-tools 5.14.0-284.79.1.el9_2, python3-perf 5.14.0-284.79.1.el9_2, +28 more
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:5364
show 9 more
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.22.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.22.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.22.1.el8_10
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:7000
  • Red Hat Enterprise Linux CRB (v. 9) libperf 5.14.0-427.42.1.el9_4, kernel-debuginfo-common-s390x 5.14.0-427.42.1.el9_4, kernel-debuginfo-common-x86_64 5.14.0-427.42.1.el9_4, kernel-debuginfo-common-aarch64 5.14.0-427.42.1.el9_4, kernel-debuginfo-common-ppc64le 5.14.0-427.42.1.el9_4
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:8617
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-kvm 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-core 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-modules 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-debug-kvm 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-debug-core 4.18.0-553.22.1.rt7.363.el8_10, +4 more
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:7001
  • Red Hat Enterprise Linux NFV (v. 9) kernel-rt 5.14.0-427.42.1.el9_4, kernel-rt-kvm 5.14.0-427.42.1.el9_4, kernel-rt-core 5.14.0-427.42.1.el9_4, kernel-rt-modules 5.14.0-427.42.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.42.1.el9_4, kernel-rt-debug-core 5.14.0-427.42.1.el9_4, +6 more
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:8617
  • Red Hat Enterprise Linux Real Time EUS (v.9.2) kernel-rt 5.14.0-284.79.1.rt14.364.el9_2, kernel-rt-core 5.14.0-284.79.1.rt14.364.el9_2, kernel-rt-modules 5.14.0-284.79.1.rt14.364.el9_2, kernel-rt-debug-core 5.14.0-284.79.1.rt14.364.el9_2, kernel-rt-modules-core 5.14.0-284.79.1.rt14.364.el9_2, kernel-rt-debug-modules 5.14.0-284.79.1.rt14.364.el9_2, +4 more Red Hat Enterprise Linux Real Time for NFV EUS (v.9.2) kernel-rt 5.14.0-284.79.1.rt14.364.el9_2, kernel-rt-kvm 5.14.0-284.79.1.rt14.364.el9_2, kernel-rt-core 5.14.0-284.79.1.rt14.364.el9_2, kernel-rt-modules 5.14.0-284.79.1.rt14.364.el9_2, kernel-rt-debug-kvm 5.14.0-284.79.1.rt14.364.el9_2, kernel-rt-debug-core 5.14.0-284.79.1.rt14.364.el9_2, +6 more
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:5365
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-core 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-modules 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-debug-core 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-debug-modules 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-modules-extra 4.18.0-553.22.1.rt7.363.el8_10, +2 more
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:7001
  • Red Hat Enterprise Linux RT (v. 9) kernel-rt 5.14.0-427.42.1.el9_4, kernel-rt-core 5.14.0-427.42.1.el9_4, kernel-rt-modules 5.14.0-427.42.1.el9_4, kernel-rt-debug-core 5.14.0-427.42.1.el9_4, kernel-rt-modules-core 5.14.0-427.42.1.el9_4, kernel-rt-debug-modules 5.14.0-427.42.1.el9_4, +4 more
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2024:8617
  • Red Hat OpenShift AI 8 rhoai/odh-rhel8-operator v2.13.1-2, rhoai/odh-dashboard-rhel8 v2.13.1-1, rhoai/odh-modelmesh-rhel8 v2.13.1-1, rhoai/odh-operator-bundle v2.13.1-2, rhoai/odh-rhel8-operator v2.14.0-24, rhoai/odh-dashboard-rhel8 v2.14.0-11, +56 more
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHBA-2024:8413
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2y ago

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.