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Fencer Vulns
high 7.0

CVE-2020-25212 json

A TOCTOU mismatch in the NFS client code in the Linux kernel before 5.8.3 could be used by local attackers to corrupt memory or possibly ha…

published 2020-09-09 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-17902

cvss
7.0
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 20%
public exploits
0
none known

Summary

A TOCTOU mismatch in the NFS client code in the Linux kernel before 5.8.3 could be used by local attackers to corrupt memory or possibly have unspecified other impact because a size check is in fs/nfs/nfs4proc.c instead of fs/nfs/nfs4xdr.c, aka CID-b4487b935452.

Patch / fix

  • linux linux_kernel 5.8.3
  • linux Debian 14, Debian 13, Debian 12 5.7.17-1

debian advisories DEBIAN-CVE-2020-25212

  • linux Ubuntu 16.04 LTS 4.4.0-190.220
  • linux Ubuntu 18.04 LTS 4.15.0-121.123
  • linux Ubuntu 20.04 LTS 5.4.0-48.52
  • linux-aws Ubuntu 16.04 LTS 4.4.0-1114.127
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1086.91
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1025.25
  • linux-gcp Ubuntu 16.04 LTS 4.15.0-1086.98~16.04.1
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1025.25

ubuntu advisories UBUNTU-CVE-2020-25212

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 8 4.18.0-305.el8
  • perf RHEL 8 4.18.0-305.el8
  • bpftool RHEL 8 4.18.0-305.el8
  • kernel-core RHEL 8 4.18.0-305.el8
  • kernel-tools RHEL 8 4.18.0-305.el8
  • python3-perf RHEL 8 4.18.0-305.el8
  • kernel-modules RHEL 8 4.18.0-305.el8
  • kernel-zfcpdump RHEL 8 4.18.0-305.el8

red hat advisories RHSA-2021:1578RHSA-2021:1739RHSA-2021:0878RHSA-2020:5441RHSA-2020:5437RHSA-2020:4279

  • 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-2020:3544-1SUSE-SU-2020:3532-1SUSE-SU-2020:3503-1SUSE-SU-2020:3501-1SUSE-SU-2020:3491-1SUSE-SU-2020:3484-1

  • 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-lp152.47.1
  • kernel-obs-qa openSUSE Leap 15.2 5.3.18-lp152.47.1
  • kernel-source openSUSE Leap 15.2 5.3.18-lp152.47.2

opensuse advisories openSUSE-SU-2021:0242-1openSUSE-SU-2020:2112-1openSUSE-SU-2020:1698-1openSUSE-SU-2020:1682-1openSUSE-SU-2020:1655-1openSUSE-SU-2020:1586-1

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-2020-25212 updated cvss 7.0

kernel: TOCTOU mismatch in the NFS client code

  • Red Hat Enterprise Linux 5 kernel Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise MRG 2 kernel
    affected: workaround, no fix planned “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.”
  • Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-305.el8, kernel-debuginfo-common-aarch64 4.18.0-305.el8, kernel-debuginfo-common-ppc64le 4.18.0-305.el8 Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-305.el8, kernel 4.18.0-305.el8, bpftool 4.18.0-305.el8, kernel-core 4.18.0-305.el8, kernel-tools 4.18.0-305.el8, python3-perf 4.18.0-305.el8, +15 more
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:1578
  • Red Hat Enterprise Linux Client (v. 7) perf 3.10.0-1160.11.1.el7, kernel 3.10.0-1160.11.1.el7, bpftool 3.10.0-1160.11.1.el7, python-perf 3.10.0-1160.11.1.el7, kernel-tools 3.10.0-1160.11.1.el7, kernel-tools-libs 3.10.0-1160.11.1.el7, +2 more Red Hat Enterprise Linux Client Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.11.1.el7
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2020:5437
  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.6) perf 3.10.0-957.70.1.el7, kernel 3.10.0-957.70.1.el7, bpftool 3.10.0-957.70.1.el7, python-perf 3.10.0-957.70.1.el7, kernel-tools 3.10.0-957.70.1.el7, kernel-tools-libs 3.10.0-957.70.1.el7, +2 more
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:0878
  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.7) perf 3.10.0-1062.45.1.el7, kernel 3.10.0-1062.45.1.el7, bpftool 3.10.0-1062.45.1.el7, python-perf 3.10.0-1062.45.1.el7, kernel-tools 3.10.0-1062.45.1.el7, kernel-tools-libs 3.10.0-1062.45.1.el7, +2 more
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:0526
  • Red Hat Enterprise Linux ComputeNode Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.11.1.el7
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2020:5437
  • Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.6) kernel-debuginfo-common-x86_64 3.10.0-957.70.1.el7
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:0878
  • Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.7) kernel-debuginfo-common-x86_64 3.10.0-1062.45.1.el7
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:0526
show 15 more
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) perf 4.14.0-115.32.1.el7a, kernel 4.14.0-115.32.1.el7a, kernel-alt 4.14.0-115.32.1.el7a, python-perf 4.14.0-115.32.1.el7a, kernel-tools 4.14.0-115.32.1.el7a, kernel-tools-libs 4.14.0-115.32.1.el7a, +3 more Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) kernel-debuginfo-common-ppc64le 4.14.0-115.32.1.el7a
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2020:4279
  • Red Hat Enterprise Linux for Real Time (v. 7) kernel-rt 3.10.0-1160.11.1.rt56.1145.el7, kernel-rt-trace 3.10.0-1160.11.1.rt56.1145.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.11.1.rt56.1145.el7 Red Hat Enterprise Linux for Real Time for NFV (v. 7) kernel-rt 3.10.0-1160.11.1.rt56.1145.el7, kernel-rt-kvm 3.10.0-1160.11.1.rt56.1145.el7, kernel-rt-trace 3.10.0-1160.11.1.rt56.1145.el7, kernel-rt-debug-kvm 3.10.0-1160.11.1.rt56.1145.el7, kernel-rt-trace-kvm 3.10.0-1160.11.1.rt56.1145.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.11.1.rt56.1145.el7
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2020:5441
  • Red Hat Enterprise Linux Real Time (v. 8) kernel-rt 4.18.0-305.rt7.72.el8, kernel-rt-core 4.18.0-305.rt7.72.el8, kernel-rt-modules 4.18.0-305.rt7.72.el8, kernel-rt-debug-core 4.18.0-305.rt7.72.el8, kernel-rt-debug-modules 4.18.0-305.rt7.72.el8, kernel-rt-modules-extra 4.18.0-305.rt7.72.el8, +2 more Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt 4.18.0-305.rt7.72.el8, kernel-rt-kvm 4.18.0-305.rt7.72.el8, kernel-rt-core 4.18.0-305.rt7.72.el8, kernel-rt-modules 4.18.0-305.rt7.72.el8, kernel-rt-debug-kvm 4.18.0-305.rt7.72.el8, kernel-rt-debug-core 4.18.0-305.rt7.72.el8, +4 more
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:1739
  • Red Hat Enterprise Linux Server (v. 7) perf 3.10.0-1160.11.1.el7, kernel 3.10.0-1160.11.1.el7, bpftool 3.10.0-1160.11.1.el7, python-perf 3.10.0-1160.11.1.el7, kernel-kdump 3.10.0-1160.11.1.el7, kernel-tools 3.10.0-1160.11.1.el7, +7 more
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2020:5437
  • Red Hat Enterprise Linux Server AUS (v. 7.4) perf 3.10.0-693.82.1.el7, kernel 3.10.0-693.82.1.el7, python-perf 3.10.0-693.82.1.el7, kernel-tools 3.10.0-693.82.1.el7, kernel-tools-libs 3.10.0-693.82.1.el7, kernel-abi-whitelists 3.10.0-693.82.1.el7, +1 more Red Hat Enterprise Linux Server E4S (v. 7.4) perf 3.10.0-693.82.1.el7, kernel 3.10.0-693.82.1.el7, python-perf 3.10.0-693.82.1.el7, kernel-tools 3.10.0-693.82.1.el7, kernel-tools-libs 3.10.0-693.82.1.el7, kernel-bootwrapper 3.10.0-693.82.1.el7, +3 more
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:0760
  • Red Hat Enterprise Linux Server EUS (v. 7.6) perf 3.10.0-957.70.1.el7, kernel 3.10.0-957.70.1.el7, bpftool 3.10.0-957.70.1.el7, python-perf 3.10.0-957.70.1.el7, kernel-kdump 3.10.0-957.70.1.el7, kernel-tools 3.10.0-957.70.1.el7, +7 more
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:0878
  • Red Hat Enterprise Linux Server EUS (v. 7.7) perf 3.10.0-1062.45.1.el7, kernel 3.10.0-1062.45.1.el7, bpftool 3.10.0-1062.45.1.el7, python-perf 3.10.0-1062.45.1.el7, kernel-kdump 3.10.0-1062.45.1.el7, kernel-tools 3.10.0-1062.45.1.el7, +7 more
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:0526
  • Red Hat Enterprise Linux Server Optional (v. 7) kernel-debuginfo-common-ppc64 3.10.0-1160.11.1.el7, kernel-debuginfo-common-x86_64 3.10.0-1160.11.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-1160.11.1.el7
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2020:5437
  • Red Hat Enterprise Linux Server Optional AUS (v. 7.4) kernel-debuginfo-common-x86_64 3.10.0-693.82.1.el7 Red Hat Enterprise Linux Server Optional E4S (v. 7.4) kernel-debuginfo-common-x86_64 3.10.0-693.82.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-693.82.1.el7
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:0760
  • Red Hat Enterprise Linux Server Optional EUS (v. 7.6) kernel-debuginfo-common-ppc64 3.10.0-957.70.1.el7, kernel-debuginfo-common-x86_64 3.10.0-957.70.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-957.70.1.el7
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:0878
  • Red Hat Enterprise Linux Server Optional EUS (v. 7.7) kernel-debuginfo-common-ppc64 3.10.0-1062.45.1.el7, kernel-debuginfo-common-x86_64 3.10.0-1062.45.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-1062.45.1.el7
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:0526
  • Red Hat Enterprise Linux Server Optional TUS (v. 7.4) kernel-debuginfo-common-x86_64 3.10.0-693.82.1.el7 Red Hat Enterprise Linux Server TUS (v. 7.4) perf 3.10.0-693.82.1.el7, kernel 3.10.0-693.82.1.el7, python-perf 3.10.0-693.82.1.el7, kernel-tools 3.10.0-693.82.1.el7, kernel-tools-libs 3.10.0-693.82.1.el7, kernel-abi-whitelists 3.10.0-693.82.1.el7, +1 more
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:0760
  • Red Hat Enterprise Linux Workstation (v. 7) perf 3.10.0-1160.11.1.el7, kernel 3.10.0-1160.11.1.el7, bpftool 3.10.0-1160.11.1.el7, python-perf 3.10.0-1160.11.1.el7, kernel-tools 3.10.0-1160.11.1.el7, kernel-tools-libs 3.10.0-1160.11.1.el7, +2 more Red Hat Enterprise Linux Workstation Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.11.1.el7
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2020:5437
  • Red Hat Virtualization 4.2 Hypervisor for RHEL 7.6 EUS perf 3.10.0-957.70.1.el7, python-perf 3.10.0-957.70.1.el7
    fixed: vendor fix “While there is no known mitigation to this flaw, configuring authentication and only mounting authenticated NFSv4 servers will significantly reduce the risk of this flaw being successfully exploited.” RHSA-2021:0878
  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.7) kernel-headers 3.10.0-1062.45.1.el7 Red Hat Enterprise Linux Server AUS (v. 7.4) kernel-headers 3.10.0-693.82.1.el7 Red Hat Enterprise Linux Server E4S (v. 7.4) kernel-headers 3.10.0-693.82.1.el7 Red Hat Enterprise Linux Server EUS (v. 7.7) kernel-headers 3.10.0-1062.45.1.el7 Red Hat Enterprise Linux Server TUS (v. 7.4) kernel-headers 3.10.0-693.82.1.el7
    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

Exploit prediction

0.28% chance of exploitation in the next 30 days, higher than 20% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 4.4 AV:L/AC:M/Au:N/C:P/I:P/A:P

Classification

Weakness
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition
  • CWE-787 Out-of-bounds Write
Technology feeds

References

Sources

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.