CVE-2021-3489
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.55%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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).
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.55% probability · 44th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-119, CWE-787
- Affected
- linux/linux kernel · canonical/ubuntu linux
- Source
- security@ubuntu.com
References
- https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=4b81ccebaeee885ab1aa1438133f2991e3a2b6eaPatch, Vendor Advisory
- https://security.netapp.com/advisory/ntap-20210716-0004/Third Party Advisory
- https://ubuntu.com/security/notices/USN-4949-1Third Party Advisory
- https://ubuntu.com/security/notices/USN-4950-1Third Party Advisory
- https://www.openwall.com/lists/oss-security/2021/05/11/10Mailing List, Third Party Advisory
- https://www.zerodayinitiative.com/advisories/ZDI-21-590/Third Party Advisory, VDB Entry
- https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=4b81ccebaeee885ab1aa1438133f2991e3a2b6eaPatch, Vendor Advisory
- https://security.netapp.com/advisory/ntap-20210716-0004/Third Party Advisory
- https://ubuntu.com/security/notices/USN-4949-1Third Party Advisory
- https://ubuntu.com/security/notices/USN-4950-1Third Party Advisory
- https://www.openwall.com/lists/oss-security/2021/05/11/10Mailing List, Third Party Advisory
- https://www.zerodayinitiative.com/advisories/ZDI-21-590/Third Party Advisory, VDB Entry
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.