CVE-2025-39986

Local kernel buffer overflow via CAN XL frame

Published Oct 15, 2025 · Updated Aug 5, 2026

Buffer overflow in the sun4i_can driver in affected Linux kernels allows local users to corrupt kernel state through a CAN XL frame. Because ndo_change_mtu is absent, an oversized MTU lets PF_PACKET pass a CAN XL packet that sun4ican_start_xmit treats as a classic CAN frame and reads its flags byte as cf->len. Reachability requires local privileges to change the CAN interface MTU and open a raw packet socket; the unchecked transmit loop can process 247 entries beyond the expected eight-byte payload.

CVSS severity7.8
High
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

Buffer overflow in the sun4i_can driver in affected Linux kernels allows local users to corrupt kernel state through a CAN XL frame. Because ndo_change_mtu is absent, an oversized MTU lets PF_PACKET pass a CAN XL packet that sun4ican_start_xmit treats as a classic CAN frame and reads its flags byte as cf->len. Reachability requires local privileges to change the CAN interface MTU and open a raw packet socket; the unchecked transmit loop can process 247 entries beyond the expected eight-byte payload.

The record

CVE
CVE-2025-39986
Published
Oct 15, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 15, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record 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=0738eff14d817a02ab082c392c96a1613006f158 <063539db42203b29d5aa2adf0cae3d68c646a6b6
  2. Affected versionversion=0738eff14d817a02ab082c392c96a1613006f158 <2e423e1990f3972cbea779883fef52c2f2acb858
  3. Affected versionversion=0738eff14d817a02ab082c392c96a1613006f158 <4f382cc887adca8478b9d3e6b81aa6698a95fff4
  4. Affected versionversion=0738eff14d817a02ab082c392c96a1613006f158 <60463a1c138900494cb3adae41142a11cd8feb3c
  5. Affected versionversion=0738eff14d817a02ab082c392c96a1613006f158 <61da0bd4102c459823fbe6b8b43b01fb6ace4a22
  6. Affected versionversion=0738eff14d817a02ab082c392c96a1613006f158 <7f7b21026a6febdb749f6f6f950427245aa86cce
  7. Affected versionversion=0738eff14d817a02ab082c392c96a1613006f158 <a61ff7ac93270d20ca426c027d6d01c8ac8e904c
  8. Affected versionversion=0738eff14d817a02ab082c392c96a1613006f158 <de77841652e57afbc46e9e1dbf51ee364fc008e1
  9. Affected versionversion=4.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0738eff14d817a02ab082c392c96a1613006f158 <063539db42203b29d5aa2adf0cae3d68c646a6b6; version=0738eff14d817a02ab082c392c96a1613006f158 <2e423e1990f3972cbea779883fef52c2f2acb858; version=0738eff14d817a02ab082c392c96a1613006f158 <4f382cc887adca8478b9d3e6b81aa6698a95fff4; version=0738eff14d817a02ab082c392c96a1613006f158 <60463a1c138900494cb3adae41142a11cd8feb3c; version=0738eff14d817a02ab082c392c96a1613006f158 <61da0bd4102c459823fbe6b8b43b01fb6ace4a22; version=0738eff14d817a02ab082c392c96a1613006f158 <7f7b21026a6febdb749f6f6f950427245aa86cce; version=0738eff14d817a02ab082c392c96a1613006f158 <a61ff7ac93270d20ca426c027d6d01c8ac8e904c; version=0738eff14d817a02ab082c392c96a1613006f158 <de77841652e57afbc46e9e1dbf51ee364fc008e1; version=4.4

Published CVSS scores

5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.8LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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

T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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