CVE-2021-3490Linux kernel eBPF bitwise ops ALU32 bounds tracking
- 7.8HighCVSS base score
- 27.4%Exploitation in 30 daysEPSS · top 1.9% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- 1Public exploitsMetasploit, Nuclei and Exploit-DB
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).
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. The public collections list a Metasploit module for it.
Show the exploits1
Metasploit modules1 module
- Linux eBPF ALU32 32-bit Invalid Bounds Tracking LPE (Metasploit module) (opens in a new tab)
exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpeRank greatdisclosed 11 May 2021
Modules, templates and exploits as listed by the Metasploit Framework (BSD-3-Clause), ProjectDiscovery's Nuclei templates (MIT) and the Exploit Database (GPLv2), read once a day. Where the data comes from
Timeline
ID reserved
By canonical
- 56 days later
· 56 days later
Published
- 3 years later
· 3 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| canonicalCNA (assigner) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 27.4% · top 1.9% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Affected products
- affected trunk – < v5.13-rc4
- affected linux-5.12.y – < v5.12.4
- affected linux-5.11.y – < v5.11.21
- affected linux-5.10.y – < v5.10.37
- affected v5.7-rc1 – < 5.7*
References
References7
- https://ubuntu.com/security/notices/USN-4950-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- https://ubuntu.com/security/notices/USN-4949-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- [oss-security] CVE-2021-3490 - Linux kernel eBPF bitwise ops ALU32 bounds tracking (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=049c4e13714ecbca567b4d5f6d563f05d431c80e (opens in a new tab)x_refsource_MISCx_transferred
- https://www.zerodayinitiative.com/advisories/ZDI-21-606/ (opens in a new tab)x_refsource_MISCx_transferred
- https://security.netapp.com/advisory/ntap-20210716-0004/ (opens in a new tab)x_refsource_CONFIRMx_transferred
- http://packetstormsecurity.com/files/164015/Linux-eBPF-ALU32-32-bit-Invalid-Bounds-Tracking-Local-Privilege-Escalation.html (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2021-26812 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2021-3490)Record last updated .