CVE-2025-38146Network attack vector

CPU lockup via wrapped MPLS label counter

Published Jul 3, 2025 · Updated Aug 5, 2026

Improper MPLS parsing in Linux Open vSwitch allows remote attackers to hang CPUs via malformed label stacks lacking a bottom marker. In key_extract_l3l4, an eight-bit label counter wraps after 256 entries, rewinds the inner network header, and keeps the receive softirq in an unbounded loop. An Open vSwitch port must receive the packet; one packet can wedge a CPU, and repeated delivery across receive queues can force a reboot while an associated upcall can disclose kernel stack data.

CVSS severity9.4
Critical
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper MPLS parsing in Linux Open vSwitch allows remote attackers to hang CPUs via malformed label stacks lacking a bottom marker. In key_extract_l3l4, an eight-bit label counter wraps after 256 entries, rewinds the inner network header, and keeps the receive softirq in an unbounded loop. An Open vSwitch port must receive the packet; one packet can wedge a CPU, and repeated delivery across receive queues can force a reboot while an associated upcall can disclose kernel stack data.

The record

CVE
CVE-2025-38146
Published
Jul 3, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-129, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 3, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=5.5
  2. Affected versionversion=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <0bdc924bfb319fb10d1113cbf091fc26fb7b1f99
  3. Affected versionversion=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <3c1906a3d50cb94fd0a10e97a1c0a40c0f033cb7
  4. Affected versionversion=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <4b9a086eedc1fddae632310386098c12155e3d0a
  5. Affected versionversion=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <69541e58323ec3e3904e1fa87a6213961b1f52f4
  6. Affected versionversion=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <8ebcd311b4866ab911d1445ead08690e67f0c488
  7. Affected versionversion=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <ad17eb86d042d72a59fd184ad1adf34f5eb36843
  8. Affected versionversion=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <f26fe7c3002516dd3c288f1012786df31f4d89e0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.5; version=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <0bdc924bfb319fb10d1113cbf091fc26fb7b1f99; version=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <3c1906a3d50cb94fd0a10e97a1c0a40c0f033cb7; version=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <4b9a086eedc1fddae632310386098c12155e3d0a; version=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <69541e58323ec3e3904e1fa87a6213961b1f52f4; version=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <8ebcd311b4866ab911d1445ead08690e67f0c488; version=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <ad17eb86d042d72a59fd184ad1adf34f5eb36843; version=fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 <f26fe7c3002516dd3c288f1012786df31f4d89e0

Published CVSS scores

9.4Linux kernel CVE teamCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H
7.8NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.0Oracle LinuxCVSS:3.1/AV:L/AC:H/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

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-129Improper Validation of Array Index
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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