CVE-2019-15791

Reference count underflow in shiftfs

HIGH
7.8
CVSS Score
Published: April 23, 2020 at 11:55 PM UTC
Updated: June 17, 2026 at 02:21 AM UTC
3 products affected across 3 vendorsLinux KernelUbuntu LinuxLinux kernel

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Severity
HIGH7.8
Exploit prediction
EPSS 1%

Description

In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, shiftfs_btrfs_ioctl_fd_replace() installs an fd referencing a file from the lower filesystem without taking an additional reference to that file. After the btrfs ioctl completes this fd is closed, which then puts a reference to that file, leading to a refcount underflow.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

5.0 kernel ≤ v < 5.0.0-35.385.3.0-11.12 ≤ v < 5.3 kernel*5.0 kernel5.3.0-11.12
Affected range stops below 5.0.0-35.38, so it looks safe — our inference, not a vendor statement
Affected range stops below 5.3 kernel*, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-672CWE-191

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