CVE-2018-12633

Severity: medium (CVSS 6.3 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2018-06-22 · updated 2026-06-17
Weakness: CWE-362

Description

An issue was discovered in the Linux kernel through 4.17.2. vbg_misc_device_ioctl() in drivers/virt/vboxguest/vboxguest_linux.c reads the same user data twice with copy_from_user. The header part of the user data is double-fetched, and a malicious user thread can tamper with the critical variables (hdr.size_in and hdr.size_out) in the header between the two fetches because of a race condition, leading to severe kernel errors, such as buffer over-accesses. This bug can cause a local denial of service and information leakage.

Affected products

Linux kernel: through 4.17.2

References

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bd23a7269834dc7c1f93e83535d16ebc44b75eba
https://bugzilla.kernel.org/show_bug.cgi?id=200131
https://github.com/torvalds/linux/commit/bd23a7269834dc7c1f93e83535d16ebc44b75eba
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bd23a7269834dc7c1f93e83535d16ebc44b75eba
https://bugzilla.kernel.org/show_bug.cgi?id=200131
https://github.com/torvalds/linux/commit/bd23a7269834dc7c1f93e83535d16ebc44b75eba

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