Buffer overflow in Linux Kernel
CVE-2021-3490
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).
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.272 (98.0th percentile), scored .
Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 98th percentile — 98.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.275 · newest: 0.272 · change: -0.003
Affected products
- Linux Kernel — versions trunk, linux-5.12.y, linux-5.11.y
- Linux Kernel — versions 5.13
- Canonical Ubuntu Linux — versions 20.04, 20.10, 21.04
Weakness classification (CWE)
Public proof-of-concept exploits
References
- ubuntu.com/security/notices/USN-4950-1 (vendor-advisory, Third Party Advisory)
- ubuntu.com/security/notices/USN-4949-1 (vendor-advisory, Third Party Advisory)
- www.openwall.com/lists/oss-security/2021/05/11/11 (mailing-list, Patch, Mailing List, Third Party Advisory)
- git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/ (Patch, Vendor Advisory)
- www.zerodayinitiative.com/advisories/ZDI-21-606/ (VDB Entry, Third Party Advisory)
- security.netapp.com/advisory/ntap-20210716-0004/ (Third Party Advisory)
- packetstormsecurity.com/files/164015/Linux-eBPF-ALU32-32-bit-Invalid-Bounds-Tra… (Exploit, VDB Entry, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-3490?
- CVE-2021-3490 is a high-severity vulnerability in Linux Kernel, classified under Improper Input Validation. CVSS score: 7.8/10. Published 2021-06-04.
- How severe is CVE-2021-3490?
- High severity. CVSS v3 base score is 7.8 out of 10.
- Is CVE-2021-3490 known to be exploited?
- 68 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.