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NVD / CVE Program· CNA Linux

CVE-2025-37878: perf/core: Fix WARN_ON(!ctx) in __free_event() for partial init

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: 0.27% (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 0ba3a4ab76fd3367b9cb680cad70182c896c795c, 6.12.26, 6.14; azl3 kernel 6.6.85.1-4 on Azure Linux 3.0 6.6.92.2-1; azl3 kernel 6.6.92.2-1 on Azure Linux 3.0 6.6.92.2-1.

Low priority for now. Upgrade to Linux Linux 0ba3a4ab76fd3367b9cb680cad70182c896c795c, 6.12.26, 6.14; azl3 kernel 6.6.85.1-4 on Azure Linux 3.0 6.6.92.2-1; azl3 kernel 6.6.92.2-1 on Azure Linux 3.0 6.6.92.2-1 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: perf/core: Fix WARN_ON(!ctx) in __free_event() for partial init Move the get_ctx(child_ctx) call and the child_event->ctx assignment to occur immediately after the child event is allocated. Ensure that child_event->ctx is non-NULL before any subsequent error path within inherit_event calls free_event(), satisfying the assumptions of the cleanup code. Details: There's no clear Fixes tag, because this bug is a side-effect of multiple interacting commits over time (up to 15 years old), not a single regression. The code initially incremented refcount then assigned context immediately after the child_event was created. Later, an early validity check for child_event was added before the refcount/assignment. Even later, a WARN_ON_ONCE() cleanup check was added, assuming event->ctx is valid if the pmu_ctx is valid. The problem is that the WARN_ON_ONCE() could trigger after the initial check passed but before child_event->ctx was assigned, violating its precondition. The solution is to assign child_event->ctx right after its initial validation. This ensures the context exists for any subsequent checks or cleanup routines, resolving the WARN_ON_ONCE(). To resolve it, defer the refcount update and child_event->ctx assignment directly after child_event->pmu_ctx is set but before checking if the parent event is orphaned. The cleanup routine depends on event->pmu_ctx being non-NULL before it verifies event->ctx is non-NULL. This also maintains the author's original intent of passing in child_ctx to find_get_pmu_context before its refcount/assignment. [ mingo: Expanded the changelog from another email by Gabriel Shahrouzi. ]

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
May 9, 2025
Updated
Nov 5, 2026
EPSS
0.2% · 20th 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 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • 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 kernelbefore 6.6.89
  • linux linux kernel6.7 and later · before 6.12.26
  • linux linux kernel6.13 and later · before 6.14.5
  • linux linux kernel6.15

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

    • 315a50c6b1c6ce191f19f3372935d8e2ed9b53a6affected
    • 7ef5aa081f989ecfecc1df02068a80aebbd3ec31 and later · before 90dc6c1e3b200812da8d0aa030e1b7fda8226d0eaffected · git
    • 1209b0b29fd472e7dbd2b06544b019dd9f9b7e51 and later · before cb56cd11feabf99e08bc18960700a53322ffcea7affected · git
    • c70ca298036c58a88686ff388d3d367e9d21acf0 and later · before 0ba3a4ab76fd3367b9cb680cad70182c896c795caffected · git
    • 6.13.12 and later · before 6.14affected · semver
    • 6.12.24 and later · before 6.12.26affected · semver
    • 6.14.3 and later · before 6.14.5affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:13linuxbefore 6.12.27-16.12.27-1

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-2025-37876May 9, 2025 · netfs: Only create /proc/fs/netfs with CONFIG_PROC_FS
    22Monitor
  • ← EarlierCVE-2025-37877May 9, 2025 · iommu: Clear iommu-dma ops on cleanup
    22Monitor
  • Later →CVE-2025-37882May 9, 2025 · usb: xhci: Fix isochronous Ring Underrun/Overrun event handling
    31Monitor

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 Linux0ba3a4ab76fd3367b9cb680cad70182c896c795cVendor (CNA)
Linux Linux6.12.26Vendor (CNA)
Linux Linux6.14Vendor (CNA)
Linux Linux6.14.5Vendor (CNA)
Linux Linux90dc6c1e3b200812da8d0aa030e1b7fda8226d0eVendor (CNA)
Linux Linuxcb56cd11feabf99e08bc18960700a53322ffcea7Vendor (CNA)
azl3 kernel 6.6.85.1-4 on Azure Linux 3.06.6.92.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kernel 6.6.92.2-1 on Azure Linux 3.06.6.92.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0Release NotesMicrosoft (MSRC)
debian:linux6.12.27-1 · Debian:13Package 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.

  • CVE-2026-31739357 days apartcrypto: tegra - Add missing CRYPTO_ALG_ASYNC
    35Monitor
  • CVE-2026-52952411 days apartiommu: Fix WARN_ON in __iommu_group_set_domain_nofail() due to reset
    35Monitor
  • CVE-2025-39803129 days apartscsi: ufs: core: Remove WARN_ON_ONCE() call from ufshcd_uic_cmd_compl()
    31Monitor
  • CVE-2026-31398329 days apartmm/rmap: fix incorrect pte restoration for lazyfree folios
    31Monitor
  • CVE-2026-46117384 days apartRDMA/mana: Remove user triggerable WARN_ON() in mana_ib_create_qp_rss()
    31Monitor
  • CVE-2023-52621409 days apartbpf: Check rcu_read_lock_trace_held() before calling bpf map helpers
    31Monitor

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-617 · Reachable Assertion

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.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

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

References

Show all references (2 more)

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

All records