Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2021-34556

CVE-2021-34556MEDIUM

n/a n/a — In the Linux kernel through 5.13.7, an unprivileged BPF program can obtain sensitive information from kernel memory via a Speculative Sto…

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   L   L   L   N  U  H  N  N    5.5   .0042   34.8     —

AFFECTED
  Product  Versions  Fixed
  n/a      n/a –     —

TIMELINE
  Jun 10  Reserved by mitre
  Aug 2   Published (CNA: mitre)
  Oct 8   ENRICHED — CVE-2021-34556. Received CVSS 5.5 and CPE data from NVD.

CWE-203 · CNA: mitre · CVSS v3.1 · 6 references · NVD status: Modified

Description

In the Linux kernel through 5.13.7, an unprivileged BPF program can obtain sensitive information from kernel memory via a Speculative Store Bypass side-channel attack because the protection mechanism neglects the possibility of uninitialized memory locations on the BPF stack.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
June 10, 2021	Reserved	Reserved by mitre
August 2, 2021	Published	Published (CNA: mitre)
October 8, 2026	ENRICHED	ENRICHED — CVE-2021-34556. Received CVSS 5.5 and CPE data from NVD.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
n/a	n/a	—	n/a	—

Weaknesses

CWE-203

References (6)

http://www.openwall.com/lists/oss-security/2021/08/01/3 [Mailing List]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch/?id=2039f26f3aca5b0e419b98f65dd36481337b86ee [Patch, Vendor Advisory]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch/?id=f5e81d1117501546b7be050c5fbafa6efd2c722c [Patch, Vendor Advisory]
https://lists.debian.org/debian-lts-announce/2021/10/msg00010.html [Mailing List, Third Party Advisory]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/565ZS55ZFEN62WVRRORT7R63RXW5F4T4/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6JKK6XNRZX5BT5QVYOKGVJ2BHFZAP5EX/

Authoritative record: CVE-2021-34556 at cve.org

Weaknesses: CWE-203

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-34556 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.