#VU91439 Buffer overflow in Linux kernel - CVE-2021-47040

Vulnerability identifier: #VU91439

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-47040

CWE-ID: CWE-119

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor: Linux Foundation

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to memory corruption within the io_remove_buffers() and io_provide_buffers_prep() functions in fs/io_uring.c. A local user can escalate privileges on the system.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Linux kernel: 5.10, 5.10 rc1, 5.10 rc2, 5.10 rc3, 5.10 rc4, 5.10 rc5, 5.10 rc7, 5.10.1, 5.10.2, 5.10.3, 5.10.4, 5.10.5, 5.10.6, 5.10.7, 5.10.8, 5.10.9, 5.10.10, 5.10.11, 5.10.12, 5.10.13, 5.10.14, 5.10.15, 5.10.16, 5.10.17, 5.10.18, 5.10.19, 5.10.20, 5.10.21, 5.10.22, 5.10.23, 5.10.24, 5.10.25, 5.10.26, 5.10.27, 5.10.28, 5.10.29, 5.10.30, 5.10.31, 5.10.32, 5.10.33, 5.10.34, 5.10.35, 5.10.36, 5.11, 5.11 rc1, 5.11.1, 5.11.2, 5.11.3, 5.11.4, 5.11.5, 5.11.6, 5.11.7, 5.11.8, 5.11.9, 5.11.10, 5.11.11, 5.11.12, 5.11.13, 5.11.14, 5.11.15, 5.11.16, 5.11.17, 5.11.18, 5.11.19, 5.11.20, 5.12, 5.12 rc1, 5.12 rc2, 5.12 rc3, 5.12 rc4, 5.12 rc6, 5.12 rc8, 5.12.1, 5.12.2, 5.12.3, 5.13 rc1, 5.13 rc4, 5.13 rc5

---

External links
https://git.kernel.org/stable/c/cbbc13b115b8f18e0a714d89f87fbdc499acfe2d
https://git.kernel.org/stable/c/51bf90901952aaac564bbdb36b2b503050c53dd9
https://git.kernel.org/stable/c/84b8c266c4bfe9ed5128e13253c388deb74b1b03
https://git.kernel.org/stable/c/38134ada0ceea3e848fe993263c0ff6207fd46e7
https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.10.37
https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.21
https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.4
https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.13

---

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.