printk: Postpone kthread startup
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Not reported
- Exploitation?/40Exploitation: unknown (data gap). No CISA SSVC exploitation rating yet
- Exposure?/25Exposure: unknown (data gap). No advisory context yet
- Reach20/20Affects Linux kernel (software on nearly every server, desktop or phone)
- Severity?/10Severity: unknown (data gap). No CVSS score or vendor rating
- No patch5/5No patch listed yet
What would change the score
- Would score about 80 if added to CISA KEV
- Would score about 75 if CISA's SSVC rates exploitation active
- Would score about 47 if advisories confirm default setups are exposed
CVE-2026-99250 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It affects Linux; no fixed version is listed yet.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 25/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
The Linux kernel's printk console subsystem, specifically its NBCON console printing kthreads, is affected. The flaw can cause SMP systems to hang during boot because the threads start too early and interfere with multiprocessor setup.
Read the original description
In the Linux kernel, the following vulnerability has been resolved: printk: Postpone kthread startup There have been various bug reports related to SMP systems hanging on boot. The reports vary but seem to have some overlap with regard to missed IPI's during SMP setup. The reports also show that reverting NBCON console usage allows the bugs to disappear. The NBCON kthreads for console printing are started very early during boot using early_initcall(). Since these kthreads are asynchronously enabling/disabling interrupts during early boot, they may be interfering with early SMP setup on some hardware platforms. Starting the console printing kthreads later has shown to avoid the hanging on systems that could previously reproduce the issue. Postpone kthread starting until after all arch initcalls have completed.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- Linux Linux
Version range not reported
- Linux Linux
6.12
Evidence 4
- Link
- Link
- Link
- Link
Corrections
None so far.
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Questions about CVE-2026-99250
Is CVE-2026-99250 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-99250?
Linux: version 6.12.Source: cve.now feed data