CVE-2020-25656 json
A flaw was found in the Linux kernel.
published 2020-12-02 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-18320
- cvss
- 4.1
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 38%
- public exploits
- 0
- none known
Summary
A flaw was found in the Linux kernel. A use-after-free was found in the way the console subsystem was using ioctls KDGKBSENT and KDSKBSENT. A local user could use this flaw to get read memory access out of bounds. The highest threat from this vulnerability is to data confidentiality.
Patch / fix
- linux linux_kernel 5.10
- linux Debian 14, Debian 13, Debian 12 5.9.6-1
debian advisories DEBIAN-CVE-2020-25656
- linux Ubuntu 16.04 LTS 4.4.0-198.230
- linux Ubuntu 18.04 LTS 4.15.0-129.132
- linux Ubuntu 20.04 LTS 5.4.0-59.65
- linux-aws Ubuntu 16.04 LTS 4.4.0-1119.133
- linux-aws Ubuntu 18.04 LTS 4.15.0-1091.96
- linux-aws Ubuntu 20.04 LTS 5.4.0-1034.35
- linux-gcp Ubuntu 16.04 LTS 4.15.0-1091.104~16.04.1
- linux-gcp Ubuntu 20.04 LTS 5.4.0-1033.35
ubuntu advisories UBUNTU-CVE-2020-25656
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-rt RHEL 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-kvm RHEL 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-core RHEL 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-modules RHEL 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-debug-kvm RHEL 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-debug-core RHEL 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-debug-modules RHEL 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-modules-extra RHEL 8 4.18.0-553.rt7.342.el8_10
red hat advisories RHSA-2024:2950RHSA-2024:3138RHSA-2021:0856RHSA-2021:0857
- kernel-syms SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.12.14-95.65.1
- kernel-source SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.12.14-95.65.1
- kernel-default SLES for SAP 12 SP4, SLES 12 SP4-LTSS, SLE Live Patching 12 SP4 +3 more 4.12.14-95.65.1
- kernel-syms SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.12.14-150.63.1
- kernel-source SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.12.14-150.63.1
- kernel-default SLES for SAP 15, SLES 15-LTSS, SLE Live Patching 15 +3 more 4.12.14-150.63.1
- kernel-vanilla SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.12.14-150.63.1
- kernel-obs-build SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.12.14-150.63.1
suse advisories SUSE-SU-2021:14630-1SUSE-SU-2020:3544-1SUSE-SU-2020:3532-1SUSE-SU-2020:3522-1SUSE-SU-2020:3513-1SUSE-SU-2020:3512-1
- kernel-source openSUSE Tumbleweed 5.14.6-1.4
- kernel-source openSUSE Tumbleweed 6.6.17-1.1
- kernel-rt openSUSE Leap 15.2 5.3.18-lp152.3.5.1
- kernel-syms-rt openSUSE Leap 15.2 5.3.18-lp152.3.5.1
- kernel-rt_debug openSUSE Leap 15.2 5.3.18-lp152.3.5.1
- kernel-source-rt openSUSE Leap 15.2 5.3.18-lp152.3.5.1
- kernel-default-base openSUSE Leap 15.2 5.3.18-lp152.50.1.lp152.8.10.1
- kernel-syms openSUSE Leap 15.2 5.3.18-lp152.50.1
opensuse advisories openSUSE-SU-2024:10728-1openSUSE-SU-2024:13704-1openSUSE-SU-2021:0242-1openSUSE-SU-2020:2112-1openSUSE-SU-2020:1906-1
- kernel-rt AlmaLinux 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-kvm AlmaLinux 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-core AlmaLinux 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-modules AlmaLinux 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-debug-kvm AlmaLinux 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-debug-core AlmaLinux 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-debug-modules AlmaLinux 8 4.18.0-553.rt7.342.el8_10
- kernel-rt-modules-extra AlmaLinux 8 4.18.0-553.rt7.342.el8_10
almalinux advisories ALSA-2024:2950ALSA-2024:3138
- kernel Rocky Linux 8 4.18.0-553.123.1.el8_10.cloud.0.1
- kernel-rt Rocky Linux 8 4.18.0-553.rt7.342.el8_10
- kernel Rocky Linux 8 4.18.0-553.el8_10
rocky linux advisories RXSA-2024:3138RLSA-2024:2950RLSA-2024:3138
- bugzilla.redhat.com/show_bug.cgi?id=1888726 advisory
- lkml.org/lkml/2020/10/29/528 advisory
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-2020-25656 updated cvss 4.1
kernel: use-after-free in read in vt_do_kdgkb_ioctl
-
Red Hat Enterprise Linux 7 perf, kernel, kernel-alt, python-perf, kernel-kdump, kernel-tools, +3 moreaffected: no fix planned “Will not fix”
-
Red Hat Enterprise MRG 2 kernelaffected: no fix planned “Out of support scope”
-
Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.el8_10, kernel 4.18.0-553.el8_10, bpftool 4.18.0-553.el8_10, kernel-core 4.18.0-553.el8_10, kernel-tools 4.18.0-553.el8_10, python3-perf 4.18.0-553.el8_10, +15 morefixed: vendor fix RHSA-2024:3138
-
Red Hat Enterprise Linux Client (v. 7) perf 3.10.0-1160.21.1.el7, kernel 3.10.0-1160.21.1.el7, bpftool 3.10.0-1160.21.1.el7, python-perf 3.10.0-1160.21.1.el7, kernel-tools 3.10.0-1160.21.1.el7, kernel-tools-libs 3.10.0-1160.21.1.el7, +2 more Red Hat Enterprise Linux Client Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.21.1.el7 Red Hat Enterprise Linux ComputeNode Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.21.1.el7fixed: vendor fix RHSA-2021:0856
-
Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.el8_10fixed: vendor fix RHSA-2024:3138
-
Red Hat Enterprise Linux for Real Time (v. 7) kernel-rt 3.10.0-1160.21.1.rt56.1158.el7, kernel-rt-trace 3.10.0-1160.21.1.rt56.1158.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.21.1.rt56.1158.el7 Red Hat Enterprise Linux for Real Time for NFV (v. 7) kernel-rt 3.10.0-1160.21.1.rt56.1158.el7, kernel-rt-kvm 3.10.0-1160.21.1.rt56.1158.el7, kernel-rt-trace 3.10.0-1160.21.1.rt56.1158.el7, kernel-rt-debug-kvm 3.10.0-1160.21.1.rt56.1158.el7, kernel-rt-trace-kvm 3.10.0-1160.21.1.rt56.1158.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.21.1.rt56.1158.el7fixed: vendor fix RHSA-2021:0857
-
Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.rt7.342.el8_10, kernel-rt-kvm 4.18.0-553.rt7.342.el8_10, kernel-rt-core 4.18.0-553.rt7.342.el8_10, kernel-rt-modules 4.18.0-553.rt7.342.el8_10, kernel-rt-debug-kvm 4.18.0-553.rt7.342.el8_10, kernel-rt-debug-core 4.18.0-553.rt7.342.el8_10, +4 more Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.rt7.342.el8_10, kernel-rt-core 4.18.0-553.rt7.342.el8_10, kernel-rt-modules 4.18.0-553.rt7.342.el8_10, kernel-rt-debug-core 4.18.0-553.rt7.342.el8_10, kernel-rt-debug-modules 4.18.0-553.rt7.342.el8_10, kernel-rt-modules-extra 4.18.0-553.rt7.342.el8_10, +2 morefixed: vendor fix RHSA-2024:2950
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Red Hat Enterprise Linux Server (v. 7) perf 3.10.0-1160.21.1.el7, kernel 3.10.0-1160.21.1.el7, bpftool 3.10.0-1160.21.1.el7, python-perf 3.10.0-1160.21.1.el7, kernel-kdump 3.10.0-1160.21.1.el7, kernel-tools 3.10.0-1160.21.1.el7, +7 more Red Hat Enterprise Linux Server Optional (v. 7) kernel-debuginfo-common-ppc64 3.10.0-1160.21.1.el7, kernel-debuginfo-common-x86_64 3.10.0-1160.21.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-1160.21.1.el7 Red Hat Enterprise Linux Workstation (v. 7) perf 3.10.0-1160.21.1.el7, kernel 3.10.0-1160.21.1.el7, bpftool 3.10.0-1160.21.1.el7, python-perf 3.10.0-1160.21.1.el7, kernel-tools 3.10.0-1160.21.1.el7, kernel-tools-libs 3.10.0-1160.21.1.el7, +2 more Red Hat Enterprise Linux Workstation Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.21.1.el7fixed: vendor fix RHSA-2021:0856
show 1 moreshow fewer
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Red Hat Enterprise Linux 5 kernel Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 morenot 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
Exploit prediction
0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=1888726 referenced PoC, tagged "exploit" by a source, unverified
- lkml.org https://lkml.org/lkml/2020/10/16/84 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 4.1 | CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N |
| NVD | 2.0 | 1.9 | AV:L/AC:M/Au:N/C:P/I:N/A:N |
Affected products
- n/a kernel
Classification
- Weakness
-
- CWE-416 Use After Free
- Technology feeds
References
-
bugzilla.redhat.com
/show_bug.cgi?id=1888726
exploit, issue-tracking, patch, third-party-advisory
-
lkml.org
/lkml/2020/10/29/528
mailing-list, patch, third-party-advisory
-
lkml.org
/lkml/2020/10/16/84
exploit, mailing-list, third-party-advisory
-
lists.debian.org
/debian-lts-announce/2020/12/msg00015.html
mailing-list, third-party-advisory
-
lists.debian.org
/debian-lts-announce/2020/12/msg00027.html
mailing-list, third-party-advisory
-
starwindsoftware.com
/security/sw-20210325-0006/
third-party-advisory
Sources
- CVE List CVE-2020-25656
- NVD CVE-2020-25656
Fencer Vulns 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.