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Fencer Vulns
high 7.8

CVE-2019-19448 json

In the Linux kernel 5.0.21 and 5.3.11, mounting a crafted btrfs filesystem image, performing some operations, and then making a syncfs syst…

published 2019-12-08 6 y ago modified 2026-06-17 4 mo ago also EUVD-2019-9069

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.1%
EPSS 2.1% chance of exploitation in 30 days, percentile 82%
public exploits
0
none known

Summary

In the Linux kernel 5.0.21 and 5.3.11, mounting a crafted btrfs filesystem image, performing some operations, and then making a syncfs system call can lead to a use-after-free in try_merge_free_space in fs/btrfs/free-space-cache.c because the pointer to a left data structure can be the same as the pointer to a right data structure.

Patch / fix

  • linux linux_kernel 4.4.233, 4.9.233, 4.14.194, 4.19.141, 5.4.60, 5.7.17, 5.8.3
  • linux Debian 14, Debian 13, Debian 12 5.7.17-1

debian advisories DEBIAN-CVE-2019-19448

  • linux Ubuntu 16.04 LTS 4.4.0-190.220
  • linux Ubuntu 18.04 LTS 4.15.0-121.123
  • linux Ubuntu 20.04 LTS 5.4.0-48.52
  • linux-aws Ubuntu 16.04 LTS 4.4.0-1114.127
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1086.91
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1025.25
  • linux-gcp Ubuntu 16.04 LTS 4.15.0-1086.98~16.04.1
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1025.25

ubuntu advisories UBUNTU-CVE-2019-19448

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-19448 updated cvss 7.8

kernel: mounting a crafted btrfs filesystem image, performing some operations, and then making a syncfs system call can lead to a use-after-free in try_merge_free_space in fs/btrfs/free-space-cache.c

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 perf, kernel, kernel-alt, python-perf, kernel-kdump, kernel-tools, +3 more Red Hat Enterprise MRG 2 kernel-rt, mrg-rt-release, kernel-rt-trace, kernel-rt-vanilla, kernel-rt-firmware
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux 5 kernel Red Hat Enterprise Linux 7 kernel, bpftool, kernel-rt, kernel-rt-kvm, kernel-rt-trace, kernel-rt-debug-kvm, +1 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.14% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/bobfuzzer/CVE/tree/master/CVE-2019-19448 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.