What’s Vulnerable › Vulnerabilities
CVE-2021-3489: Linux kernel eBPF RINGBUF map oversized allocation
- Severity: high (CVSS 7.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.5% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2021-06-04 · updated 2026-06-17
- Weakness: CWE-119
Description
The eBPF RINGBUF bpf_ringbuf_reserve() function in the Linux kernel did not check that the allocated size was smaller than the ringbuf size, allowing an attacker to perform out-of-bounds writes within the kernel and therefore, arbitrary code execution. This issue was fixed via commit 4b81ccebaeee ("bpf, ringbuf: Deny reserve of buffers larger than ringbuf") (v5.13-rc4) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. It was introduced via 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it") (v5.8-rc1).
Affected products
- Canonical Ubuntu Linux: 20.04, 20.10, 21.04
- Linux kernel: from 5.8 before 5.10.37; from 5.11 before 5.11.21; from 5.12 before 5.12.4; 5.13, 5.13-rc1, 5.13-rc2, 5.13-rc3 — fixed in 5.10.37, 5.11.21, 5.12.4
How to fix
Upgrade to a fixed version: Linux kernel 5.10.37, 5.11.21, 5.12.4. Check the vendor advisory for mitigations.
References
- https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=4b81ccebaeee885ab1aa1438133f2991e3a2b6ea
- https://security.netapp.com/advisory/ntap-20210716-0004/
- https://ubuntu.com/security/notices/USN-4949-1
- https://ubuntu.com/security/notices/USN-4950-1
- https://www.openwall.com/lists/oss-security/2021/05/11/10
- https://www.zerodayinitiative.com/advisories/ZDI-21-590/
- https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=4b81ccebaeee885ab1aa1438133f2991e3a2b6ea
- https://security.netapp.com/advisory/ntap-20210716-0004/
- https://ubuntu.com/security/notices/USN-4949-1
- https://ubuntu.com/security/notices/USN-4950-1
- https://www.openwall.com/lists/oss-security/2021/05/11/10
- https://www.zerodayinitiative.com/advisories/ZDI-21-590/
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