CVE-2026-43323sched/fair: Fix zero_vruntime tracking fix
- 5.5MediumCVSS base score
- 0.12%Exploitation in 30 daysEPSS · top 98% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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().
Timeline
ID reserved
By Linux
- 7 days later
· 7 days later
Published
- 6 months later
· 6 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Analyzed | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.12% · top 98% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.
Affected products
- affected d2fc2dcfce47a56ffd414783003cc966c742c8a9 – < c089147074ed96ff4330739a0559394c19a3dfc8
- affected 99673934a89febe664e704550216638dcb2336a8 – < 87573883c30f1a8555ff720836bb6ea231058539
- affected 978d4fe59665c13db692ba96839f9c52d69f13f3 – < fb61ffb3fb30a161eb5404c27fc7635e275beafd
- affected b3d99f43c72b56cf7a104a364e7fb34b0702828b – < 1319ea57529e131822bab56bf417c8edc2db9ae8
- affected 6.12.78 – < 6.12.81
- affected 6.18.17 – < 6.18.22
- affected 6.19.7 – < 6.19.12
References
References4
- https://git.kernel.org/stable/c/c089147074ed96ff4330739a0559394c19a3dfc8 (opens in a new tab)
- https://git.kernel.org/stable/c/87573883c30f1a8555ff720836bb6ea231058539 (opens in a new tab)
- https://git.kernel.org/stable/c/fb61ffb3fb30a161eb5404c27fc7635e275beafd (opens in a new tab)
- https://git.kernel.org/stable/c/1319ea57529e131822bab56bf417c8edc2db9ae8 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-28607 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-43323)Record last updated .