CVE-2026-10681
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SMP race in `thread_idx_alloc()` lets concurrent `k_object_alloc(K_OBJ_THREAD)` callers share a kernel-object permission slot
rank 20 = 0 + 18 + 0 + 2 + 0
rank@v1 · backlog
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.00119 · without this subject the record ranks 20
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 7.0, from NVD · without this subject the record ranks 2
It is getting worse, not staying still
FIRST EPSS series, rescorings and bad loads removed
no persisting rise in 365 days · without this subject the record ranks 20
How much of the world it touches
NVD CPE configurations
1 product in the CPE ranges · without this subject the record ranks 18
Someone else already set the date
CISA KEV remediation due date
no CISA due date · without this subject the record ranks 20
$5,510 = $4.99M incident cost x 0.9280467328949208 exposure x 0.00119 likelihood
udv@v1 · unaudited · wrong for you until you say what you run
$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.
Hindsight · the state
Foresight · where to check next
This record is one instance of CWE-362, concurrent execution using shared resource with improper synchronization ('race condition'). The index holds 2680 prior instances of this class, 12 KEV-listed. The nearest of its KEV-listed records are drawn beside this. taxonomy@v1
Sources disagree here.
Both shown, dated. We don't pick winners. disagreement-rules@v1
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Harm, if it fires from the vector and the weakness
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CISA KEV & Federal Remediation Deadline from the record and CISA
The fix, and how long it's been waiting.
Exploit Status & Known PoCs a ladder, not a score
Current rung: Nothing observed in held sources.
- RUNG 1Nothing observed in held sources
- RUNG 2Proof-of-concept published
- RUNG 3Exploited in the wild · CISA KEV listed
- RUNG 4Ransomware campaign use known
A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.
Attack path
What it is stated by the CNA
In Zephyr's userspace dynamic-objects subsystem, thread_idx_alloc() in kernel/userspace/userspace.c allocated a new thread permission index from the global _thread_idx_map[] bitmap without holding lists_lock. On SMP systems, two user-mode threads invoking the k_object_alloc(K_OBJ_THREAD) syscall concurrently can both observe the same low free bit, perform the same non-atomic RMW to clear it, and return the identical tidx. The two newly created K_OBJ_THREAD objects are then assigned the same thread_id, so the two user threads alias a single bit position in every kernel object's perms[] bitfield: any subsequent grant of access on a kernel object to one thread is implicitly a grant to the oth receipt
Read the rest of the CNA's description
er, defeating userspace ACL isolation. A secondary lost-update window between the unlocked &=~BIT() in alloc and the locked |= BIT() in thread_idx_free() can also leak entries from the thread-index pool. The defect is reachable from any user-mode thread via the unrestricted __syscall k_object_alloc and is gated on CONFIG_USERSPACE, CONFIG_DYNAMIC_OBJECTS, and CONFIG_SMP. The flaw was introduced when the per-thread permission index was added in 2018 and is present in every release up to and including v4.4.0. Fixed by holding lists_lock across the bitmap RMW and the permissions clear (and inlining the obj_list traversal that previously took the lock itself).
NVD's analysis a second authority
- severity
- 7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- weakness
- CWE-362
- affected versions
- zephyrproject zephyr >= 2.0.0 < 4.5.0
- also scored by
- [email protected] 6.5 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L
The CNA scored it 6.5 and NVD 7. Both are shown because both were published; we do not pick one.
check it yourself github.com github.com receipt
Movement the material steps
Show all 3 observations
3 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt
The full biography
The record had been public for 1 month when this index was last written.
The pattern, elsewhere
This record is one instance of CWE-362, concurrent execution using shared resource with improper synchronization ('race condition'). The index holds 2680 prior instances of this class, 12 KEV-listed. The nearest of its KEV-listed records are drawn beside this. [email protected]
"Matches n of m" counts the attributes the two records can both be compared on: the CVSS metrics they share a version of, any weakness class beyond this one, and the vendor. fit-rules@v1
2680 records in this class held. The six above are drawn from the ones CISA has listed as exploited, ranked by how much of the record matches this one. That is why every one of them is KEV-listed: the pool is, so the colour on those spokes says nothing the pool has not already said.
No curated product neighbourhood is held for this product, so the records above are the nearest this index can name. The neighbourhood table covers a small set of products and is extended by hand.
Siblings and hubs
Records related to this one
No record cites this identifier and it carries no alias. Its defect family is below.
Its defect family
zephyrproject zephyr
Of the 4 records in this family, this is the only one whose title names smp thread_idx_alloc lets.
Grouped by shared product and weakness, not by shared vulnerability. Each record's own state is on its own page.
Family membership: held values
This record is one of a group, and the group's page describes all of them. This page is kept and dated, and the defect family's own page is the one we offer for indexing: the whole group.
Browse the index from here
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What usually comes next
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