CVE-2025-39748

Kernel warning via inconsistent JSET range refinement

Published Sep 11, 2025 · Updated Sep 11, 2025

Improper BPF verifier range refinement in Linux allows local users to trigger a kernel warning with a crafted JSET path. On an unreachable fall-through path, the verifier narrows the register tnum after JSET without discarding prior ranges, producing contradictory unsigned bounds. Reachability requires local access sufficient to submit a BPF program; the published behavior is a warning, not code execution or data access.

CVSS severity5.5
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper BPF verifier range refinement in Linux allows local users to trigger a kernel warning with a crafted JSET path. On an unreachable fall-through path, the verifier narrows the register tnum after JSET without discarding prior ranges, producing contradictory unsigned bounds. Reachability requires local access sufficient to submit a BPF program; the published behavior is a warning, not code execution or data access.

The record

CVE
CVE-2025-39748
Published
Sep 11, 2025
Updated
Sep 11, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 11, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 11, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2fd0c26bacd90ef26522bd3169000a4715bf151f
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6279846b9b2532e1b04559ef8bd0dec049f29383
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <80a6b11862a7cfdf691e8f9faee89cfea219f098
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f01e06930444cab289a8783017af9b64255bd103

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2fd0c26bacd90ef26522bd3169000a4715bf151f; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6279846b9b2532e1b04559ef8bd0dec049f29383; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <80a6b11862a7cfdf691e8f9faee89cfea219f098; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f01e06930444cab289a8783017af9b64255bd103

Published CVSS scores

5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Oracle LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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