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Fencer Vulns
high 7.0

CVE-2021-26708 json

A local privilege escalation was discovered in the Linux kernel before 5.10.13.

published 2021-02-05 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-13497

cvss
7.0
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 75%
public exploits
0
none known

Summary

A local privilege escalation was discovered in the Linux kernel before 5.10.13. Multiple race conditions in the AF_VSOCK implementation are caused by wrong locking in net/vmw_vsock/af_vsock.c. The race conditions were implicitly introduced in the commits that added VSOCK multi-transport support.

Patch / fix

  • linux linux_kernel 5.10.13
  • netapp baseboard_management_controller_500f_firmware 15.3
  • netapp baseboard_management_controller_a250_firmware 15.3
  • linux Debian 14, Debian 13, Debian 12 5.10.13-1

debian advisories DEBIAN-CVE-2021-26708

  • linux-hwe-5.8 Ubuntu 20.04 LTS 5.8.0-43.49~20.04.1
  • linux-oem-5.6 Ubuntu 20.04 LTS 5.6.0-1047.51
  • linux-oem-5.10 Ubuntu 20.04 LTS 5.10.0-1016.17
  • linux-riscv-5.8 Ubuntu 20.04 LTS 5.8.0-16.18~20.04.1

ubuntu advisories UBUNTU-CVE-2021-26708

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 4.18.0-240.22.1.el8_3
  • perf RHEL 8 4.18.0-240.22.1.el8_3
  • bpftool RHEL 8 4.18.0-240.22.1.el8_3
  • kernel-core RHEL 8 4.18.0-240.22.1.el8_3
  • kernel-tools RHEL 8 4.18.0-240.22.1.el8_3
  • python3-perf RHEL 8 4.18.0-240.22.1.el8_3
  • kernel-modules RHEL 8 4.18.0-240.22.1.el8_3
  • kernel-zfcpdump RHEL 8 4.18.0-240.22.1.el8_3

red hat advisories RHSA-2021:1093RHSA-2021:1081

  • kernel-source openSUSE Tumbleweed 5.14.6-1.4
  • kernel-source openSUSE Tumbleweed 6.6.17-1.1

opensuse advisories openSUSE-SU-2024:10728-1openSUSE-SU-2024:13704-1

  • kernel-abi-whitelists AlmaLinux 8 4.18.0-240.22.1.el8_3

almalinux advisories ALSA-2021:1093

  • linux Arch Linux 5.10.13.arch1-1
  • linux-hardened Arch Linux 5.10.13.hardened1-1
  • linux-zen Arch Linux 5.10.13.zen1-1

arch linux advisories AVG-1512AVG-1513AVG-1514

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-2021-26708 updated cvss 7.8

kernel: race conditions caused by wrong locking in net/vmw_vsock/af_vsock.c

  • Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-240.22.1.el8_3, kernel-debuginfo-common-aarch64 4.18.0-240.22.1.el8_3, kernel-debuginfo-common-ppc64le 4.18.0-240.22.1.el8_3 Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-240.22.1.el8_3, kernel 4.18.0-240.22.1.el8_3, bpftool 4.18.0-240.22.1.el8_3, kernel-core 4.18.0-240.22.1.el8_3, kernel-tools 4.18.0-240.22.1.el8_3, python3-perf 4.18.0-240.22.1.el8_3, +15 more
    fixed: vendor fix RHSA-2021:1093
  • Red Hat Enterprise Linux Real Time (v. 8) kernel-rt 4.18.0-240.22.1.rt7.77.el8_3, kernel-rt-core 4.18.0-240.22.1.rt7.77.el8_3, kernel-rt-modules 4.18.0-240.22.1.rt7.77.el8_3, kernel-rt-debug-core 4.18.0-240.22.1.rt7.77.el8_3, kernel-rt-debug-modules 4.18.0-240.22.1.rt7.77.el8_3, kernel-rt-modules-extra 4.18.0-240.22.1.rt7.77.el8_3, +2 more Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt 4.18.0-240.22.1.rt7.77.el8_3, kernel-rt-kvm 4.18.0-240.22.1.rt7.77.el8_3, kernel-rt-core 4.18.0-240.22.1.rt7.77.el8_3, kernel-rt-modules 4.18.0-240.22.1.rt7.77.el8_3, kernel-rt-debug-kvm 4.18.0-240.22.1.rt7.77.el8_3, kernel-rt-debug-core 4.18.0-240.22.1.rt7.77.el8_3, +4 more
    fixed: vendor fix RHSA-2021:1081
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, kernel-alt, python-perf, +9 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +82 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

Exploit prediction

1.60% chance of exploitation in the next 30 days, higher than 75% 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 6.9 AV:L/AC:M/Au:N/C:C/I:C/A:C

Classification

Weakness
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.