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CVE-2019-15794

MEDIUMCVSS 6.7/10EPSS 1.16%

Last modified

CVE-2019-15794 is a medium-severity vulnerability rated 6.7/10 on the CVSS scale. 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->vm_file in their mmap handlers. On error the original value is not restored, and the reference is put for the file to which vm_file points. EPSS estimates a 1.16% chance of exploitation in the next 30 days.

Description

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->vm_file in their mmap handlers. On error the original value is not restored, and the reference is put for the file to which vm_file points. On upstream kernels this is not an issue, as no callers dereference vm_file following after call_mmap() returns an error. However, the aufs patchs change mmap_region() to replace the fput() using a local variable with vma_fput(), which will fput() vm_file, leading to a refcount underflow.

Metrics

CVSS 3.1
6.7/10

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

EPSS Probability
1.16%

63.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
LinuxLinux Kernel5.0
LinuxLinux Kernel5.3
CanonicalUbuntu Linux18.04
CanonicalUbuntu Linux19.10

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2019-15794?
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->vm_file in their mmap handlers. On error the original value is not restored, and the reference is put for the file to which vm_file points. On upstream kernels this is not an issue, as no callers dereference vm_file following after call_mmap() returns an error. However, the aufs patchs change mmap_region() to replace the fput() using a local variable with vma_fput(), which will fput() vm_file, leading to a refcount underflow.
How severe is CVE-2019-15794?
CVE-2019-15794 has a CVSS score of 6.7/10 (MEDIUM severity). The EPSS model estimates a 1.16% probability of exploitation in the next 30 days.
How do I fix CVE-2019-15794?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2019-15794?

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Source: NVD / NIST