CVE-2021-34556

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Summary

CVECVE-2021-34556
StatePUBLISHED
Assignermitre
Source PriorityCVE Program / NVD first with legacy fallback
Published2021-08-02 05:15:07 UTC
Updated2026-10-08 21:17:35 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

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

EPSS: 0.004190000 probability, percentile 0.343190000 (date 2026-10-10)

Problem Types: CWE-203 | n/a

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
2.0[email protected]Primary2.1AV:L/AC:L/Au:N/C:P/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

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

CVSS v2.0 Breakdown

Access Vector
Local
Access Complexity
Low
Authentication
None
Confidentiality
Partial
Integrity
None
Availability
None

AV:L/AC:L/Au:N/C:P/I:N/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Debian Debian Linux 9.0 All All All
Operating System Fedoraproject Fedora 33 All All All
Operating System Fedoraproject Fedora 34 All All All
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Na N/a affected n/a Not specified

References

ReferenceSourceLinkTags
[SECURITY] [DLA 2785-1] linux-4.19 security update af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Mailing List, Third Party Advisory
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch, Vendor Advisory
[SECURITY] Fedora 34 Update: kernel-5.13.8-200.fc34 - package-announce - Fedora Mailing-Lists af854a3a-2127-422b-91ae-364da2661108 lists.fedoraproject.org
oss-security - [CVE-2021-34556,CVE-2021-35477] Linux kernel BPF protection against Speculative Store Bypass can be bypassed to disclose arbitrary kernel memory af854a3a-2127-422b-91ae-364da2661108 www.openwall.com Mailing List
[SECURITY] Fedora 33 Update: kernel-5.13.8-100.fc33 - package-announce - Fedora Mailing-Lists af854a3a-2127-422b-91ae-364da2661108 lists.fedoraproject.org
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch, Vendor Advisory
[SECURITY] Fedora 34 Update: kernel-5.13.8-200.fc34 - package-announce - Fedora Mailing-Lists MITRE lists.fedoraproject.org
[SECURITY] Fedora 33 Update: kernel-5.13.8-100.fc33 - package-announce - Fedora Mailing-Lists MITRE lists.fedoraproject.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 178844 Debian Security Update for linux-4.19 (DLA 2785-1)
  • 180199 Debian Security Update for linux (CVE-2021-34556)
  • 198515 Ubuntu Security Notification for Linux kernel Vulnerabilities (USN-5092-1)
  • 198523 Ubuntu Security Notification for Linux kernel Vulnerabilities (USN-5092-2)
  • 198524 Ubuntu Security Notification for Linux kernel (OEM) Vulnerabilities (USN-5096-1)
  • 198542 Ubuntu Security Notification for Linux kernel (OEM) Vulnerabilities (USN-5115-1)
  • 198563 Ubuntu Security Notification for Linux kernel Vulnerabilities (USN-5137-1)
  • 198565 Ubuntu Security Notification for Linux kernel Vulnerabilities (USN-5137-2)
  • 281775 Fedora Security Update for kernel (FEDORA-2021-4d4d3866ca)
  • 281780 Fedora Security Update for kernel (FEDORA-2021-54ee631709)
  • 352503 Amazon Linux Security Advisory for kernel: ALAS2-2021-1696
  • 353156 Amazon Linux Security Advisory for kernel : ALAS2KERNEL-5.10-2022-004
  • 610418 Google Pixel Android June 2022 Security Patch Missing
  • 671134 EulerOS Security Update for kernel (EulerOS-SA-2021-2688)
  • 671137 EulerOS Security Update for kernel (EulerOS-SA-2021-2713)
  • 671268 EulerOS Security Update for kernel (EulerOS-SA-2022-1196)
  • 751137 OpenSUSE Security Update for the Linux Kernel (openSUSE-SU-2021:1271-1)
  • 751160 OpenSUSE Security Update for the Linux Kernel (openSUSE-SU-2021:3179-1)
  • 751163 SUSE Enterprise Linux Security Update for the Linux Kernel (SUSE-SU-2021:3206-1)
  • 751170 OpenSUSE Security Update for the Linux Kernel (openSUSE-SU-2021:3205-1)
  • 751336 OpenSUSE Security Update for the Linux Kernel (openSUSE-SU-2021:1460-1)
  • 751349 OpenSUSE Security Update for the Linux Kernel (openSUSE-SU-2021:1477-1)
  • 751381 SUSE Enterprise Linux Security Update for the Linux Kernel (SUSE-SU-2021:3748-1)
  • 751437 SUSE Enterprise Linux Security Update for the Linux Kernel (SUSE-SU-2021:3876-1)
  • 751441 OpenSUSE Security Update for the Linux Kernel (openSUSE-SU-2021:3876-1)
  • 751451 SUSE Enterprise Linux Security Update for the Linux Kernel (SUSE-SU-2021:3935-1)
  • 751473 SUSE Enterprise Linux Security Update for the Linux Kernel (SUSE-SU-2021:3969-1)
  • 751476 SUSE Enterprise Linux Security Update for the Linux Kernel (SUSE-SU-2021:3972-1)
  • 900289 CBL-Mariner Linux Security Update for kernel 5.10.52.1
  • 900304 CBL-Mariner Linux Security Update for kernel 5.10.57.1
  • 900319 CBL-Mariner Linux Security Update for kernel 5.10.60.1
  • 900922 Common Base Linux Mariner (CBL-Mariner) Security Update for kernel (6566-1)
  • 903470 Common Base Linux Mariner (CBL-Mariner) Security Update for kernel (4989)
  • 906090 Common Base Linux Mariner (CBL-Mariner) Security Update for kernel (4989-1)

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