CASCACascade Atlas

Evidence dossier

CVE-2025-38352

posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()

Exploited in the wild (CISA KEV since Sep 4, 2025). Linux reports CVSS 3.1 7.8. EPSS estimates 1.3% exploit likelihood as of Aug 27, 2026.

60.8–71.2Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del() If an exiting non-autoreaping task has already passed exit_notify() and calls handle_posix_cpu_timers() from IRQ, it can be reaped by its parent or debugger right after unlock_task_sighand(). If a concurrent posix_cpu_timer_del() runs at that moment, it won't be able to detect timer->it.cpu.firing != 0: cpu_timer_task_rcu() and/or lock_task_sighand() will fail. Add the tsk->exit_state check into run_posix_cpu_timers() to fix this. This fix is not needed if CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y, because exit_task_work() is called before exit_notify(). But the check still makes sense, task_work_add(&tsk->posix_cputimers_work.work) will fail anyway in this case.

State
PUBLISHED
Published
Jul 22, 2025
Updated
Aug 5, 2026
Evidence coverage
85%

Evidence chronology

What was known when

Download this view's receipt →
  1. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: Linux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Linux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability
    Original evidence ↗
  2. Source dateSource date omittedFirst observed by CASCA
    CISA-ADP

    Record text: CISA ADP Vulnrichment

    Inspect raw assertion
    Field
    container
    Value
    CISA ADP Vulnrichment
    Original evidence ↗
  3. Source dateSource date omittedFirst observed by CASCA
    CVE Program

    Record text: CVE Program Container

    Inspect raw assertion
    Field
    container
    Value
    CVE Program Container
    Original evidence ↗
  4. Source dateSource date omittedFirst observed by CASCA
    Linux

    Record text: posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()

    Inspect raw assertion
    Field
    container
    Value
    posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 1.28% probability · 67.88th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.012780000000; percentile 0.678810000000
    Original evidence ↗
ExploitationCatalog member

CISA KEV · catalog date Sep 4, 2025 · first observed Jul 19, 2026

Exploit likelihood1.28%

FIRST EPSS · score date Aug 27, 2026 · 67.9th percentile · first observed Aug 27, 2026

SeverityCVSS 7.8

Linux · CVSS 3.1 · first observed Aug 6, 2026 · same-version scores align in this snapshot

Evidence detail

Source limits and decisions

Why each evidence state has this value

casca-unknown-reasons-v1
Exploitation statusEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Aug 27, 2026
Resolution
None
Exploit likelihoodEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Aug 27, 2026
Resolution
None
Severity assessmentEvidence supported

Eligible evidence is present for this bounded claim.

Revision
casca-direct-cvss-eligibility-v1
Cutoff
Aug 27, 2026
Resolution
None
Affected productsSource-reported scope

The cited source assertion is retained while canonical product linkage remains open.

Revision
casca-factor-d-obligations-v1
Cutoff
Aug 27, 2026
Resolution
Resolve identity

Source comparison

Who said what

CISA KEVOriginal assertion
Exploitation cataloged

Linux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Linux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
CISA-ADPIndependent enrichment
Record text

CISA ADP Vulnrichment

Inspect raw assertion
Field
container
Value
CISA ADP Vulnrichment
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CVE ProgramDerivative copy
Record text

CVE Program Container

Inspect raw assertion
Field
container
Value
CVE Program Container
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
LinuxOriginal assertion
Record text

posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()

Inspect raw assertion
Field
container
Value
posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

1.28% probability · 67.88th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.012780000000; percentile 0.678810000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
9Underlying assertions
2Canonical products
9Target assertions
0Constraint assertions

Grouped from 2 configuration nodes in this exact snapshot. Visual grouping is navigational; asset exposure and root cause require cited evidence.

Identity source boundaries
  • Cpe dictionary1,775,266 records · observed through 2026-07-21T06:45:29.809Z27d65b0f-b718-4b4f-bb79-c47c68d09dfa
  • Cpe match643,502 records · observed through 2026-07-21T08:13:17.697Z955dae73-7302-438b-aee1-058d7cc5d48e

4 scope groups

Linux · source assertedLinuxLinuxDirect source scope
Affected: 0bdd2ed4138ec04e09b4f8165981efc99e439f55 to before 78a4b8e3795b31dae58762bc091bb0f4f74a2200 (git comparison)Affected: 0bdd2ed4138ec04e09b4f8165981efc99e439f55 to before c076635b3a42771ace7d276de8dc3bc76ee2ba1b (git comparison)Affected: 0bdd2ed4138ec04e09b4f8165981efc99e439f55 to before 2f3daa04a9328220de46f0d5c919a6c0073a9f0b (git comparison)Affected: 0bdd2ed4138ec04e09b4f8165981efc99e439f55 to before 764a7a5dfda23f69919441f2eac2a83e7db6e5bb (git comparison)Affected: 0bdd2ed4138ec04e09b4f8165981efc99e439f55 to before 2c72fe18cc5f9f1750f5bc148cf1c94c29e106ff (git comparison)Affected: 0bdd2ed4138ec04e09b4f8165981efc99e439f55 to before c29d5318708e67ac13c1b6fc1007d179fb65b4d7 (git comparison)Affected: 0bdd2ed4138ec04e09b4f8165981efc99e439f55 to before 460188bc042a3f40f72d34b9f7fc6ee66b0b757b (git comparison)Affected: 0bdd2ed4138ec04e09b4f8165981efc99e439f55 to before f90fff1e152dedf52b932240ebbd670d83330eca (git comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "0bdd2ed4138ec04e09b4f8165981efc99e439f55", "lessThan": "78a4b8e3795b31dae58762bc091bb0f4f74a2200", "versionType": "git"}, {"status": "affected", "version": "0bdd2ed4138ec04e09b4f8165981efc99e439f55", "lessThan": "c076635b3a42771ace7d276de8dc3bc76ee2ba1b", "versionType": "git"}, {"status": "affected", "version": "0bdd2ed4138ec04e09b4f8165981efc99e439f55", "lessThan": "2f3daa04a9328220de46f0d5c919a6c0073a9f0b", "versionType": "git"}, {"status": "affected", "version": "0bdd2ed4138ec04e09b4f8165981efc99e439f55", "lessThan": "764a7a5dfda23f69919441f2eac2a83e7db6e5bb", "versionType": "git"}, {"status": "affected", "version": "0bdd2ed4138ec04e09b4f8165981efc99e439f55", "lessThan": "2c72fe18cc5f9f1750f5bc148cf1c94c29e106ff", "versionType": "git"}, {"status": "affected", "version": "0bdd2ed4138ec04e09b4f8165981efc99e439f55", "lessThan": "c29d5318708e67ac13c1b6fc1007d179fb65b4d7", "versionType": "git"}, {"status": "affected", "version": "0bdd2ed4138ec04e09b4f8165981efc99e439f55", "lessThan": "460188bc042a3f40f72d34b9f7fc6ee66b0b757b", "versionType": "git"}, {"status": "affected", "version": "0bdd2ed4138ec04e09b4f8165981efc99e439f55", "lessThan": "f90fff1e152dedf52b932240ebbd670d83330eca", "versionType": "git"}]
Linux · source assertedLinuxLinuxDirect source scope
Affected: 2.6.36Unaffected: 0 to before 2.6.36 (semver comparison)Unaffected: 5.4.295 through 5.4.* (semver comparison)Unaffected: 5.10.239 through 5.10.* (semver comparison)Unaffected: 5.15.186 through 5.15.* (semver comparison)Unaffected: 6.1.142 through 6.1.* (semver comparison)Unaffected: 6.6.94 through 6.6.* (semver comparison)Unaffected: 6.12.34 through 6.12.* (semver comparison)Unaffected: 6.15.3 through 6.15.* (semver comparison)Unaffected: 6.16 through * (original_commit_for_fix comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "2.6.36"}, {"status": "unaffected", "version": "0", "lessThan": "2.6.36", "versionType": "semver"}, {"status": "unaffected", "version": "5.4.295", "versionType": "semver", "lessThanOrEqual": "5.4.*"}, {"status": "unaffected", "version": "5.10.239", "versionType": "semver", "lessThanOrEqual": "5.10.*"}, {"status": "unaffected", "version": "5.15.186", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.142", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.94", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.34", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.15.3", "versionType": "semver", "lessThanOrEqual": "6.15.*"}, {"status": "unaffected", "version": "6.16", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}]
NVD CPE · OPERATING SYSTEMdebiandebian_linuxVulnerable target · 1 assertions
Version 11.0Canonical identity product-3ccb4bc87dfae98fa2f2a06435fe5b3d9be78572fb958a89f2d7a96b4066447eLinked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    1 · node/0 · match 0
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    fa6feec2-9f11-4643-8827-749718254fed
NVD CPE · OPERATING SYSTEMlinuxlinux_kernelVulnerable target · 8 assertions
Any version (unconstrained) (>= 2.6.36, < 5.4.295); Any version (unconstrained) (>= 5.11, < 5.15.186); Any version (unconstrained) (>= 5.16, < 6.1.142); Any version (unconstrained) (>= 5.5, < 5.10.239); Any version (unconstrained) (>= 6.13, < 6.15.3); Any version (unconstrained) (>= 6.2, < 6.6.94); Any version (unconstrained) (>= 6.7, < 6.12.34); Version 6.16Canonical identity product-0eda7a801761be4590f267cf319481c8c0aaa30546d99cc064edf77989ce05c9Linked exact
Scope supported
Inspect raw assertions
  1. cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 6
    Logic
    OR
    Version bounds
    from including 6.13; through excluding 6.15.3
    Match ID
    0541c761-bd5e-4c1a-8432-83b375d7eb92
  2. cpe:2.3:o:linux:linux_kernel:6.16:rc1:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 7
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    6d4894db-ccfe-4602-b1bf-3960b2e19a01
  3. cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 0
    Logic
    OR
    Version bounds
    from including 2.6.36; through excluding 5.4.295
    Match ID
    aa6f945b-f2bb-4787-b4ad-104604aaf325
  4. cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 4
    Logic
    OR
    Version bounds
    from including 6.2; through excluding 6.6.94
    Match ID
    304e3f01-7d7a-4908-994e-7f95c5c00b06
  5. cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 2
    Logic
    OR
    Version bounds
    from including 5.11; through excluding 5.15.186
    Match ID
    d96f2c0d-0d4a-4658-ad34-d8a626ea422d
  6. cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 5
    Logic
    OR
    Version bounds
    from including 6.7; through excluding 6.12.34
    Match ID
    4ffa54aa-cdfe-4591-bd07-72813d0948f4
  7. cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 1
    Logic
    OR
    Version bounds
    from including 5.5; through excluding 5.10.239
    Match ID
    c3d14f4c-a21e-465d-a928-5cce684e2b98
  8. cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 3
    Logic
    OR
    Version bounds
    from including 5.16; through excluding 6.1.142
    Match ID
    459b4e94-fe0e-434d-b782-95e3a5ffc6b1

Affected-product evidence

Accepted scope and product mapping

0 canonical links · 2 source-reported links

Source-reported scopeSource-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Vendor specified only by source · Product specified only by source

Source class
Direct cve affected
Assertions
2
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
6e9838ea-2c41-44d1-bcb6-970c511726eb8246c0bb-690c-4101-92ce-5f489f63a88e
Source-reported scopeSource-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Vendor specified only by source · Product specified only by source

Source class
Nvd cpe vulnerable target
Assertions
9
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
194e6c62-c325-4898-b46e-f743dbf9a6e61e6f4e72-1653-4918-b288-4cf08c589aaa281a6512-539d-43dd-b719-bb40d9ab1df434feb532-966c-4cf7-b69c-c2e4b9db1c0b46a2647f-51dd-45e8-8249-b9ef38e6a5cc5ad0b015-c357-423f-bfda-5d9ee557a93f6039df67-d2ed-45d9-81a2-6ab25635c0e1950549a3-436f-47e8-9426-f36a20532a0ddf265203-229c-4607-a6ed-e4afe9c6790c

Assessments

CVSS by origin

7.4
CVE Program sourceCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
7.8
CVE Program sourceCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.4
CISA-ADPCVSS 3.1 · role unknown · display onlyDirect record assessment retained outside normalized eligibilityCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
7.8
LinuxCVSS 3.1 · role unknown · display onlyDirect record assessment retained outside normalized eligibilityCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Direct CVE/CNA normalized decisions

7.8Priority eligible

Linux

CVSS 3.1 · Primary · Original assertion · rank 1

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Validation
Valid match
Recomputed
7.8
Decision reason
Evidence supported
Policy
casca-direct-cvss-eligibility-v1
7.4Priority eligible

CISA-ADP

CVSS 3.1 · Secondary · Independent enrichment · rank 2

CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Validation
Valid match
Recomputed
7.4
Decision reason
Evidence supported
Policy
casca-direct-cvss-eligibility-v1

Assessments are retained side by side under closed precedence. Cascade never averages CVSS.

Evidence boundaries

  • KEV membership is authoritative for the catalog, not proof of exposure in any environment.
  • EPSS is a dated model probability and not an individual-environment prediction.
  • Affected or fixed status applies only to the exact cited product and version scope; remaining scope stays source-scoped.
  • NVD-carried upstream facts remain derivative; independent corroboration requires a separately authored source.
  • Only NVD metrics validated under the generation-bound calculator are Public Priority eligible; direct CVE record metrics remain display-only.
  • NVD CVSS source eligibility is closed: NVD-authored, exact record-source, or registered same-CVE container origin; unmapped sources remain display-only.
  • Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.
  • OSV aggregation and OSV-converted NVD material are not independent corroboration.
  • Red Hat facts are vendor assertions for the exact supplied products.
  • Nonmembership and not-yet-observed states are not proof of safety.