# CVE-2026-43323: linux: In the Linux kernel, the following vulnerability has been resolved: sched/fair: Fix zero_vruntime tracking fix John... CVE-2026-43323 is fixed in 37 products on 1 platform, first by ALAS2023-2026-1695, released May 8, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-43323 - Priority: Routine - CVSS: 5.5 (medium) - EPSS: 0.0012 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: May 8, 2026 ## Description In the Linux kernel, the following vulnerability has been resolved: sched/fair: Fix zero_vruntime tracking fix John reported that stress-ng-yield could make his machine unhappy and managed to bisect it to commit b3d99f43c72b ("sched/fair: Fix zero_vruntime tracking"). The combination of yield and that commit was specific enough to hypothesize the following scenario: Suppose we have 2 runnable tasks, both doing yield. Then one will be eligible and one will not be, because the average position must be in between these two entities. Therefore, the runnable task will be eligible, and be promoted a full slice (all the tasks do is yield after all). This causes it to jump over the other task and now the other task is eligible and current is no longer. So we schedule. Since we are runnable, there is no {de,en}queue. All we have is the __{en,de}queue_entity() from {put_prev,set_next}_task(). But per the fingered commit, those two no longer move zero_vruntime. All that moves zero_vruntime are tick and full {de,en}queue. This means, that if the two tasks playing leapfrog can reach the critical speed to reach the overflow point inside one tick's worth of time, we're up a creek. Additionally, when multiple cgroups are involved, there is no guarantee the tick will in fact hit every cgroup in a timely manner. Statistically speaking it will, but that same statistics does not rule out the possibility of one cgroup not getting a tick for a significant amount of time -- however unlikely. Therefore, just like with the yield() case, force an update at the end of every slice. This ensures the update is never more than a single slice behind and the whole thing is within 2 lag bounds as per the comment on entity_key(). ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool6.12 amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | bpftool6.12-debuginfo amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | bpftool6.18 amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | kernel-livepatch-6.12.83-113.160 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | kernel-livepatch-6.18.25-52.107 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | kernel6.12 amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | kernel6.12-debuginfo amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | kernel6.12-debuginfo-common-aarch64 amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | kernel6.12-debuginfo-common-x86_64 amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | kernel6.12-devel amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | kernel6.12-headers amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | kernel6.12-modules-extra amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | kernel6.12-modules-extra-common amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | kernel6.12-tools amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | kernel6.12-tools-debuginfo amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | kernel6.12-tools-devel amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | kernel6.18 amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | kernel6.18-devel amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | kernel6.18-headers amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | kernel6.18-tools amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | linux Debian 14 | 6.19.12-1 | [DEBIAN-CVE-2026-43323](https://patchblox.com/security/data/fix/linux/debian-cve-2026-43323.md) | May 15, 2026 | | Linux | perf6.12 amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | perf6.12-debuginfo amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | perf6.18 amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | python3-perf6.12 amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | python3-perf6.12-debuginfo amzn 2023 | 1:6.12.83-113.160.amzn2023 | [ALAS2023-2026-1695](https://patchblox.com/security/data/fix/linux/alas2023-2026-1695.md) | May 8, 2026 | | Linux | python3-perf6.18 amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | | Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 | --- Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.