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NVD / CVE Program· CNA Linux

CVE-2025-21767: clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.17% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 0fb534187d2355f6c8f995321e76d1ccd1262ac1, 5.10.235, 5.13.

Low priority for now. Upgrade to Linux Linux 0fb534187d2355f6c8f995321e76d1ccd1262ac1, 5.10.235, 5.13 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context The following bug report happened with a PREEMPT_RT kernel: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2012, name: kwatchdog preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 get_random_u32+0x4f/0x110 clocksource_verify_choose_cpus+0xab/0x1a0 clocksource_verify_percpu.part.0+0x6b/0x330 clocksource_watchdog_kthread+0x193/0x1a0 It is due to the fact that clocksource_verify_choose_cpus() is invoked with preemption disabled. This function invokes get_random_u32() to obtain random numbers for choosing CPUs. The batched_entropy_32 local lock and/or the base_crng.lock spinlock in driver/char/random.c will be acquired during the call. In PREEMPT_RT kernel, they are both sleeping locks and so cannot be acquired in atomic context. Fix this problem by using migrate_disable() to allow smp_processor_id() to be reliably used without introducing atomic context. preempt_disable() is then called after clocksource_verify_choose_cpus() but before the clocksource measurement is being run to avoid introducing unexpected latency.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Feb 27, 2025
Updated
Oct 15, 2026
EPSS
0.1% · 7th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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  • when exploit code appears or is weaponized
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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.10.50 and later · before 5.10.235
  • linux linux kernel5.12.17 and later · before 5.13
  • linux linux kernel5.13.2 and later · before 5.15.179
  • linux linux kernel5.16 and later · before 6.1.129
  • linux linux kernel6.2 and later · before 6.6.79
  • linux linux kernel6.7 and later · before 6.12.16
  • linux linux kernel6.13 and later · before 6.13.4
  • linux linux kernel6.14

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 193e14e68e907b2a7a936a7726accbaa4df25a4d, 155d3c5d24ee13cafa6236b49fc02b240a511d59, 5.14affected
    • d9b40ebd448e437ffbc65f013836f98252279a82 and later · before d9c217fadfcff7a8df58567517d1e4253f3fd243affected · git
    • 7560c02bdffb7c52d1457fa551b9e745d4b9e754 and later · before 60f54f0d4ea530950549a8263e6fdd70a40490a4affected · git
    • 7560c02bdffb7c52d1457fa551b9e745d4b9e754 and later · before 852805b6cbdb69c298a8fc9fbe79994c95106e04affected · git
    • 7560c02bdffb7c52d1457fa551b9e745d4b9e754 and later · before 8783ceeee797d9aa9cfe150690fb9d0bac8cc459affected · git
    • 7560c02bdffb7c52d1457fa551b9e745d4b9e754 and later · before cc3d79e7c806cb57d71c28a4a35e7d7fb3265faaaffected · git
    • 7560c02bdffb7c52d1457fa551b9e745d4b9e754 and later · before 0fb534187d2355f6c8f995321e76d1ccd1262ac1affected · git
    • 7560c02bdffb7c52d1457fa551b9e745d4b9e754 and later · before 6bb05a33337b2c842373857b63de5c9bf1ae2a09affected · git
    • 5.10.50 and later · before 5.10.235affected · semver
    • 5.12.17 and later · before 5.13affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.129-16.1.129-1
Debian:13linuxbefore 6.12.16-16.12.16-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2025-21765Feb 27, 2025 · ipv6: use RCU protection in ip6_default_advmss()
    22Monitor
  • ← EarlierCVE-2025-21766Feb 27, 2025 · ipv4: use RCU protection in __ip_rt_update_pmtu()
    22Monitor
  • Later →CVE-2025-21768Feb 27, 2025 · net: ipv6: fix dst ref loops in rpl, seg6 and ioam6 lwtunnels
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0fb534187d2355f6c8f995321e76d1ccd1262ac1Vendor (CNA)
Linux Linux5.10.235Vendor (CNA)
Linux Linux5.13Vendor (CNA)
Linux Linux5.14Vendor (CNA)
Linux Linux60f54f0d4ea530950549a8263e6fdd70a40490a4Vendor (CNA)
Linux Linux6bb05a33337b2c842373857b63de5c9bf1ae2a09Vendor (CNA)
Linux Linux852805b6cbdb69c298a8fc9fbe79994c95106e04Vendor (CNA)
Linux Linux8783ceeee797d9aa9cfe150690fb9d0bac8cc459Vendor (CNA)
Linux Linuxcc3d79e7c806cb57d71c28a4a35e7d7fb3265faaVendor (CNA)
Linux Linuxd9c217fadfcff7a8df58567517d1e4253f3fd243Vendor (CNA)
debian:linux6.1.129-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-667 · Improper Locking

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (10 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records