VulnerabilityPublished 23 Oct 2026

CVE-2026-98942: Linux kernel · sched_ext: Build the cid tables privately and publish them with RCU

Source GCVE Database

Authoritative record:CVE-2026-98942· Medium

Not known to be exploited : upgrade to 3a773220d39ba993dfe5d135f8b610be10794d5d or 0e1a74369bdbc357d3d9713734418d914a981553 when convenient.

Data as of 26 Oct 2026, 13:47 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3a773220d39ba993dfe5d135f8b610be10794d5d, 0e1a74369bdbc357d3d9713734418d914a981553

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-rh9v-mpgh-f53x

What to do

Upgrade Linux kernel to 3a773220d39ba993dfe5d135f8b610be10794d5d or 0e1a74369bdbc357d3d9713734418d914a981553.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ e9b55af47edf6e60c9a47b5604c3e15c5162ec86, < 3a773220d39ba993dfe5d135f8b610be10794d5d	Fixed in 3a773220d39ba993dfe5d135f8b610be10794d5d
LinuxLinux	Affected ≥ e9b55af47edf6e60c9a47b5604c3e15c5162ec86, < 0e1a74369bdbc357d3d9713734418d914a981553	Fixed in 0e1a74369bdbc357d3d9713734418d914a981553
LinuxLinux	Affected =7.2	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Build the cid tables privately and publish them with RCU The cid tables are visible to the cid kfuncs while being modified: the first enable publishes the global pointers before filling them, ops.init_cids() overrides rewrite them in place, and re-enables rebuild them in place. A racing TRACING or SYSCALL program can read unfilled entries, including uninitialized memory in the kmalloc'd tables, or torn topo updates. Tie the tables' lifetimes to the root sched instead: each root enable builds a fresh set privately and publishes the per-table __rcu globals once the layout is final, and root disable unpublishes and RCU-frees the set. A non-NULL global is now always a fully built table which stays valid for the reader's RCU read section, and lookups stay two loads. Kfuncs treat NULL as no-mapping, also after the scheduler exits instead of reporting the stale last mapping. The cid kfuncs are available whether the root scheduler is cid-form or cpu-form, the latter to allow gradual migration to cids. Every root therefore builds and publishes a default mapping. Every reader must either be gated on scheduler liveness or NULL-check inside an RCU read section. Fix the two kfuncs that were neither: scx_bpf_this_cid() read the table with no RCU or preemption protection and scx_bpf_task_cid() relied on KF_RCU, which doesn't put a sleepable program in an RCU read section. The hotplug callbacks are instead serialized by retiring the tables inside the cpus_read_lock() section that clears scx_root. v2: Document why every root builds the tables (desc + cid.c comment).

References

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