CVE-2021-3490

Linux kernel eBPF bitwise ops ALU32 bounds tracking

HIGH

7.8

CVSS Score

Published: June 4, 2021 at 01:40 AM UTC

Updated: June 17, 2026 at 04:05 AM UTC

2 products affected across 2 vendorsLinux KernelUbuntu Linux

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Severity

HIGH7.8

Exploit prediction

EPSS 27%

Description

The eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) in the Linux kernel did not properly update 32-bit bounds, which could be turned into out of bounds reads and writes in the Linux kernel and therefore, arbitrary code execution. This issue was fixed via commit 049c4e13714e ("bpf: Fix alu32 const subreg bound tracking on bitwise operations") (v5.13-rc4) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. The AND/OR issues were introduced by commit 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking") (5.7-rc1) and the XOR variant was introduced by 2921c90d4718 ("bpf:Fix a verifier failure with xor") ( 5.10-rc1).

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Ubuntu Linux · Canonicalrubygems

95%

20.04 20.10 21.04

Linux Kernel · Linux

95%

5.10 ≤ v < 5.10.375.11 ≤ v < 5.11.215.12 ≤ v < 5.12.4linux-5.10.y ≤ v < v5.10.37linux-5.11.y ≤ v < v5.11.21linux-5.12.y ≤ v < v5.12.4trunk ≤ v < v5.13-rc4v5.7-rc1 ≤ v < 5.7*5.10.y 5.11.y 5.12.y 5.13 5.13 rc1 5.13 rc2 5.13 rc3 5.7-rc1 trunk

Affected range stops below 5.10.37, so it looks safe — our inference, not a vendor statement

Affected range stops below 5.11.21, so it looks safe — our inference, not a vendor statement

Affected range stops below 5.12.4, so it looks safe — our inference, not a vendor statement

Affected range stops below 5.7*, so it looks safe — our inference, not a vendor statement

Affected range stops below v5.10.37, so it looks safe — our inference, not a vendor statement

Affected range stops below v5.11.21, so it looks safe — our inference, not a vendor statement

Affected range stops below v5.12.4, so it looks safe — our inference, not a vendor statement

Affected range stops below v5.13-rc4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (7)

x_refsource_MISCExploitThird Party AdvisoryVDB Entry

Source: [email protected]

http://packetstormsecurity.com/files/164015/Linux-eBPF-ALU32-32-bit-Invalid-Bounds-Tracking-Local-Privilege-Escalation.html

x_refsource_MISCPatchVendor Advisory

Source: [email protected]

https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=049c4e13714ecbca567b4d5f6d563f05d431c80e

x_refsource_CONFIRMThird Party Advisory

Source: [email protected]

https://security.netapp.com/advisory/ntap-20210716-0004/

Vendor Advisoryx_refsource_UBUNTUThird Party Advisory

Source: [email protected]

https://ubuntu.com/security/notices/USN-4949-1

Vendor Advisoryx_refsource_UBUNTUThird Party Advisory

Source: [email protected]

https://ubuntu.com/security/notices/USN-4950-1

Mailing Listx_refsource_MLISTPatchThird Party Advisory

Source: [email protected]

https://www.openwall.com/lists/oss-security/2021/05/11/11

x_refsource_MISCThird Party AdvisoryVDB Entry

Source: [email protected]

https://www.zerodayinitiative.com/advisories/ZDI-21-606/

CVSS

7.8HIGHcanonical

Attack Vector: LOCAL
Complexity: HIGH
Privileges: LOW
User Interaction: NONE
Scope: CHANGED
Confidentiality: HIGH
Integrity: HIGH
Availability: HIGH

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-20CWE-787CWE-125

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