Description
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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 5.7.17-1 | — |
| Debian 13 | linux | 5.7.17-1 | — |
| Debian 12 | linux | 5.7.17-1 | — |
| Debian 9 | linux | 4.9.240-1 | DLA-2420-1 |
| Debian 9 | linux-4.19 | 4.19.146-1~deb9u1 | DLA-2385-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | linux-raspi-realtime | No fix yet | — |
| Ubuntu 22.04 LTS | linux-realtime +1 | No fix yet | — |
| Ubuntu 20.04 LTS | linux | 5.4.0-48.52 | — |
| Ubuntu 20.04 LTS | linux-aws +2 | 5.4.0-1025.25 | — |
| Ubuntu 20.04 LTS | linux-azure | 5.4.0-1026.26 | — |
| Ubuntu 20.04 LTS | linux-kvm | 5.4.0-1024.24 | — |
| Ubuntu 20.04 LTS | linux-raspi | 5.4.0-1019.21 | — |
| Ubuntu 20.04 LTS | linux-raspi2 +1 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-riscv | 5.4.0-34.38 | — |
| Ubuntu 18.04 LTS | linux | 4.15.0-121.123 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-aws | 4.15.0-1086.91 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-aws-5.4 +2 | 5.4.0-1025.25~18.04.1 | — |
| Ubuntu 18.04 LTS | linux-azure-4.15 | 4.15.0-1099.110 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-azure-5.4 | 5.4.0-1026.26~18.04.1 | — |
| Ubuntu 18.04 LTS | linux-gcp +11 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-gcp-4.15 | 4.15.0-1086.98 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-gke-4.15 | 4.15.0-1072.76 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-hwe-5.4 | 5.4.0-48.52~18.04.1 | — |
| Ubuntu 18.04 LTS | linux-kvm | 4.15.0-1077.79 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-oem | 4.15.0-1099.109 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-oracle | 4.15.0-1057.62 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-raspi-5.4 | 5.4.0-1019.21~18.04.1 | — |
| Ubuntu 18.04 LTS | linux-raspi2 | 4.15.0-1073.78 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-snapdragon | 4.15.0-1089.98 | USN-4578-1 |
| Ubuntu 16.04 LTS | linux | 4.4.0-190.220 | — |
| Ubuntu 16.04 LTS | linux-aws | 4.4.0-1114.127 | — |
| Ubuntu 16.04 LTS | linux-aws-hwe | 4.15.0-1085.90~16.04.1 | USN-4578-1 |
| Ubuntu 16.04 LTS | linux-azure | 4.15.0-1098.109~16.04.1 | USN-4578-1 |
| Ubuntu 16.04 LTS | linux-gcp | 4.15.0-1086.98~16.04.1 | USN-4578-1 |
| Ubuntu 16.04 LTS | linux-hwe | 4.15.0-120.122~16.04.1 | USN-4578-1 |
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
| Ubuntu 16.04 LTS | linux-kvm | 4.4.0-1080.87 | — |
| Ubuntu 16.04 LTS | linux-oracle | 4.15.0-1056.61~16.04.1 | USN-4578-1 |
| Ubuntu 16.04 LTS | linux-raspi2 | 4.4.0-1139.148 | — |
| Ubuntu 16.04 LTS | linux-snapdragon | 4.4.0-1143.152 | — |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro FIPS 20.04 LTS | linux-aws-fips +2 | No fix yet | — |
| Ubuntu Pro FIPS 18.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS 16.04 LTS | linux-fips | No fix yet | — |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-aws-fips | 5.4.0-1069.73+fips2 | — |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-azure-fips | 5.4.0-1073.76+fips1 | — |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-gcp-fips | 5.4.0-1067.71~20.04.1 | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-aws-fips | 4.15.0-2030.31 | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-azure-fips | 4.15.0-2012.14 | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-fips | 4.15.0-1044.50 | — |
| Ubuntu Pro FIPS-updates 16.04 LTS | linux-fips | 4.4.0-1046.51 | — |
| Ubuntu Pro 14.04 LTS | linux | No fix yet | — |
| Ubuntu Pro 14.04 LTS | linux-aws | 4.4.0-1078.82 | — |
| Ubuntu Pro 14.04 LTS | linux-azure | 4.15.0-1098.109~14.04.1 | USN-4578-1 |
| Ubuntu Pro 14.04 LTS | linux-lts-xenial | 4.4.0-190.220~14.04.1 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | kernel-livepatch-4.14.198-152.320 | 1.0-0.amzn2 | ALAS2-2020-1495 |
| Amazon Linux 2 | perf +8 | 4.14.198-152.320.amzn2 | ALAS2-2020-1495 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | kernel-uek +5 | 4.1.12-124.54.6.1.el7uek | ELSA-2021-9459, ELSA-2020-5913 |
| Oracle Linux 7 | perf +5 | 4.14.35-2025.402.2.1.el7uek | ELSA-2020-5913 |
Advisories 6
- USN-4578-1 linux, linux-aws, linux-aws-hwe, linux-azure, linux-azure-4.15, linux-gcp, linux-gcp-4.15, linux-gke-4.15, linux-hwe, linux-kvm, linux-oem, linux-oracle, linux-raspi2, linux-snapdragon vulnerabilities Ubuntu Security Notices (USN) · Sep 7, 2026
- DLA-2385-1 linux-4.19 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-2420-1 linux - security update Debian Security (DSA / DLA) · Mar 9, 2026
- ALAS2-2020-1495 Important: kernel security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Jun 29, 2023
- ELSA-2021-9459 Important: Unbreakable Enterprise kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Sep 22, 2021
- ELSA-2020-5913 Important: Unbreakable Enterprise kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Nov 10, 2020
References
- https://github.com/bobfuzzer/CVE/tree/master/CVE-2019-19448
- https://security.netapp.com/advisory/ntap-20200103-0001/
- [debian-lts-announce] 20200928 [SECURITY] [DLA 2385-1] linux-4.19 security update mailing-list
- USN-4578-1 vendor-advisory
- [debian-lts-announce] 20201030 [SECURITY] [DLA 2420-1] linux security update mailing-list
- [debian-lts-announce] 20201031 [SECURITY] [DLA 2420-2] linux regression update mailing-list