CVE-2020-27171

An issue was discovered in the Linux kernel before 5.11.8. kernel/bpf/verifier.c has an off-by-one error (with a resultant integer underflow) affecting out-of-bounds speculation on pointer arithmetic, leading to side-channel attacks that defeat Spectre mitigations and obtain sensitive information from kernel memory, aka CID-10d2bb2e6b1d.

CVSS 3.1

6.0CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H

EPSS

0.6% chance of exploitation in the next 30 days; higher than 47% of CVEs (scores of 2026-10-25)

CWE

CWE-193

Published

2021-03-20

Modified

2026-10-08

Record from

the NVD, synced 2026-10-19

Affected

• canonical:ubuntu_linux
• debian:debian_linux
• fedoraproject:fedora
• linux:linux_kernel

References

• http://packetstormsecurity.com/files/162117/Kernel-Live-Patch-Security-Notice-LSN-0075-1.html
• http://www.openwall.com/lists/oss-security/2021/03/24/5
• https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.8
• https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/patch/?id=10d2bb2e6b1d8c4576c56a748f697dbeb8388899
• https://lists.debian.org/debian-lts-announce/2021/03/msg00035.html

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