How severe is CVE-2019-15791?

CVE-2019-15791 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.

Is CVE-2019-15791 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-15791?

CVE-2019-15791 primarily affects Linux Linux Kernel. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-15791?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2019-15791 published?

CVE-2019-15791 was published on 2020-04-24 and last updated on 2026-06-17.

CVE-2019-15791

CVE-2019-15791 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-191.

Key facts

Severity: High (CVSS 3.x base score 7.1)
CVSS v2: 4.6
EPSS exploit prediction: 1% (67th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-191
Affected product: Linux Linux Kernel
Published: 2020-04-24
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2019-15791?: 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.
How severe is CVE-2019-15791?: CVE-2019-15791 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.
Is CVE-2019-15791 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-15791?: CVE-2019-15791 primarily affects Linux Linux Kernel. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-15791?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2019-15791 published?: CVE-2019-15791 was published on 2020-04-24 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:o:linux:linux_kernel:5.0:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.3:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:19.04:*:*:*:*:*:*:*

More vulnerabilities in Linux Linux Kernel

CVE-2023-2163 — Critical (CVSS 10.0): Incorrect verifier pruning in BPF in Linux Kernel >=5.4 leads to unsafe code paths being incorrectly marked as safe,…
CVE-2015-8104 — Critical (CVSS 10.0): The KVM subsystem in the Linux kernel through 4.2.6, and Xen 4.3.x through 4.6.x, allows guest OS users to cause a…
CVE-2015-1421 — Critical (CVSS 10.0): Use-after-free vulnerability in the sctp_assoc_update function in net/sctp/associola.c in the Linux kernel before…
CVE-2014-2523 — Critical (CVSS 10.0): net/netfilter/nf_conntrack_proto_dccp.c in the Linux kernel through 3.13.6 uses a DCCP header pointer incorrectly,…
CVE-2010-2495 — Critical (CVSS 10.0): The pppol2tp_xmit function in drivers/net/pppol2tp.c in the L2TP implementation in the Linux kernel before 2.6.34 does…
CVE-2010-2521 — Critical (CVSS 10.0): Multiple buffer overflows in fs/nfsd/nfs4xdr.c in the XDR implementation in the NFS server in the Linux kernel before…

All CVEs affecting Linux Linux Kernel →

Other CWE-191 (Integer Underflow) vulnerabilities

CVE-2007-0063 — Critical (CVSS 10.0): Integer underflow in the DHCP server in EMC VMware Workstation before 5.5.5 Build 56455 and 6.x before 6.0.1 Build…
CVE-2026-53176 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: IB/isert: Reject login PDUs shorter than…
CVE-2026-37534 — Critical (CVSS 9.8): Integer underflow vulnerability in Open-SAE-J1939 thru commit b6caf884df46435e539b1ecbf92b6c29b345bdfe (2025-11-30) in…
CVE-2025-52471 — Critical (CVSS 9.8): ESF-IDF is the Espressif Internet of Things (IOT) Development Framework. An integer underflow vulnerability has been…
CVE-2025-29909 — Critical (CVSS 9.8): CryptoLib provides a software-only solution using the CCSDS Space Data Link Security Protocol - Extended Procedures…
CVE-2024-47606 — Critical (CVSS 9.8): GStreamer is a library for constructing graphs of media-handling components. An integer underflow has been detected in…

Browse all CWE-191 (Integer Underflow) vulnerabilities →