CVE-2019-15794: Reference counting error in overlayfs/shiftfs error path when used in conjuction with aufs
Last updated 27 August 2026
Other sources
Overlayfs in the Linux kernel and shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, both replace vma->vmfile in their mmap handlers. On error the original value is not restored, and the reference is put for the file to which vmfile points. On upstream kernels this is not an issue, as no callers dereference vmfile following after callmmap() returns an error. However, the aufs patchs change mmapregion() to replace the fput() using a local variable with vmafput(), which will fput() vmfile, leading to a refcount underflow.
— Launchpad
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 6.1.176-1Fixed in 6.1.187-1Fixed in 6.12.107-1Fixed in 7.1.13-1
Event History
Frequently Asked Questions
What is the vulnerability ID for this vulnerability?
The vulnerability ID for this vulnerability is CVE-2019-15794.
What is the affected software?
The affected software includes the Linux kernel versions 5.0.0-1022.25 and 5.3.0-1008.9, as well as the Ubuntu 5.0 and 5.3 kernel series.
What is the impact of this vulnerability?
The vulnerability allows an attacker to overwrite arbitrary files in the underlying file system, potentially leading to privilege escalation or unauthorized access to sensitive information.
How do I fix CVE-2019-15794?
To fix CVE-2019-15794, it is recommended to update the affected software to the latest version provided by the Ubuntu or Linux kernel source.
Are there any references for this vulnerability?
Yes, you can find references for this vulnerability at the following URLs: [Reference 1](https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=270d16ae48a4dbf1c7e25e94cc3e38b4bea37635), [Reference 2](https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=ef81780548d20a786cc77ed4203fca146fd81ce3), [Reference 3](https://usn.ubuntu.com/usn/usn-4208-1)