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NVD / CVE Program· CNA Linux

CVE-2025-37949: xenbus: Use kref to track req lifetime

MediumCVSS 5.5 · v3.1—No exploit Fix available

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: 0.24% (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 0e94a246bb6d9538010b6c02d2b1d4717a97b2e5, 1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27, 2466b0f66795c3c426cacc8998499f38031dbb59.
  • Severity is disputed: the assigning authority (CNA) scores it 7.8, NVD 5.5.

Low priority for now. Upgrade to Linux Linux 0e94a246bb6d9538010b6c02d2b1d4717a97b2e5, 1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27, 2466b0f66795c3c426cacc8998499f38031dbb59 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: xenbus: Use kref to track req lifetime Marek reported seeing a NULL pointer fault in the xenbus_thread callstack: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: e030:__wake_up_common+0x4c/0x180 Call Trace: <TASK> __wake_up_common_lock+0x82/0xd0 process_msg+0x18e/0x2f0 xenbus_thread+0x165/0x1c0 process_msg+0x18e is req->cb(req). req->cb is set to xs_wake_up(), a thin wrapper around wake_up(), or xenbus_dev_queue_reply(). It seems like it was xs_wake_up() in this case. It seems like req may have woken up the xs_wait_for_reply(), which kfree()ed the req. When xenbus_thread resumes, it faults on the zero-ed data. Linux Device Drivers 2nd edition states: "Normally, a wake_up call can cause an immediate reschedule to happen, meaning that other processes might run before wake_up returns." ... which would match the behaviour observed. Change to keeping two krefs on each request. One for the caller, and one for xenbus_thread. Each will kref_put() when finished, and the last will free it. This use of kref matches the description in Documentation/core-api/kref.rst

Published
May 20, 2025
Updated
Oct 15, 2026
EPSS
0.2% · 15th 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
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.5
CNA · Linux
7.8
2.3 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2025-37949

When you'll hear from us

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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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
debiandebian linux

Affected versions

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

  • debian debian linux11.0
  • linux linux kernel5.5 and later · before 5.10.238
  • linux linux kernel5.11 and later · before 5.15.183
  • linux linux kernel5.16 and later · before 6.1.139
  • linux linux kernel4.11 and later · before 5.4.294
  • linux linux kernel6.7 and later · before 6.12.29
  • linux linux kernel6.13 and later · before 6.14.7
  • linux linux kernel6.2 and later · before 6.6.91
  • 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

    • 4.11affected
    • fd8aa9095a95c02dcc35540a263267c29b8fda9d and later · before 0e94a246bb6d9538010b6c02d2b1d4717a97b2e5affected · git
    • fd8aa9095a95c02dcc35540a263267c29b8fda9d and later · before f1bcac367bc95631afbb918348f30dec887d0e1baffected · git
    • fd8aa9095a95c02dcc35540a263267c29b8fda9d and later · before 4d260a5558df4650eb87bc41b2c9ac2d6b2ba447affected · git
    • fd8aa9095a95c02dcc35540a263267c29b8fda9d and later · before 8b02f85e84dc6f7c150cef40ddb69af5a25659e5affected · git
    • fd8aa9095a95c02dcc35540a263267c29b8fda9d and later · before cbfaf46b88a4c01b64c4186cdccd766c19ae644caffected · git
    • fd8aa9095a95c02dcc35540a263267c29b8fda9d and later · before 8e9c8a0393b5f85f1820c565ab8105660f4e8f92affected · git
    • fd8aa9095a95c02dcc35540a263267c29b8fda9d and later · before 2466b0f66795c3c426cacc8998499f38031dbb59affected · git
    • fd8aa9095a95c02dcc35540a263267c29b8fda9d and later · before 1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27affected · git
    • before 4.11not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.140-16.1.140-1
Debian:13linuxbefore 6.12.29-16.12.29-1

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-2025-37945May 20, 2025 · net: phy: allow MDIO bus PM ops to start/stop state machine for phylink-controlled PHY
    22Monitor
  • ← EarlierCVE-2025-37948May 20, 2025 · arm64: bpf: Add BHB mitigation to the epilogue for cBPF programs
    22Monitor
  • Later →CVE-2025-37952May 20, 2025 · ksmbd: Fix UAF in __close_file_table_ids
    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 Linux0e94a246bb6d9538010b6c02d2b1d4717a97b2e5Vendor (CNA)
Linux Linux1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27Vendor (CNA)
Linux Linux2466b0f66795c3c426cacc8998499f38031dbb59Vendor (CNA)
Linux Linux4d260a5558df4650eb87bc41b2c9ac2d6b2ba447Vendor (CNA)
Linux Linux8b02f85e84dc6f7c150cef40ddb69af5a25659e5Vendor (CNA)
Linux Linux8e9c8a0393b5f85f1820c565ab8105660f4e8f92Vendor (CNA)
Linux Linuxcbfaf46b88a4c01b64c4186cdccd766c19ae644cVendor (CNA)
Linux Linuxf1bcac367bc95631afbb918348f30dec887d0e1bVendor (CNA)
debian:linux6.1.140-1 · 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-476 · NULL Pointer Dereference

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 (9 more)

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

All records