CVE-2026-74664

Kernel panic via undersized echoed flow-update reply buffer

Published Aug 22, 2026 · Updated Aug 22, 2026

Denial of service in the Open vSwitch component of Linux allows local users to trigger a kernel panic through crafted flow updates. ovs_flow_cmd_new() sizes an echoed reply buffer from a short request UFID, then ovs_flow_cmd_fill_info() writes the longer key identifier found by fallback lookup. The path requires permission to issue flow updates; reaching BUG_ON after an EMSGSIZE failure crashes the kernel without reported data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the Open vSwitch component of Linux allows local users to trigger a kernel panic through crafted flow updates. ovs_flow_cmd_new() sizes an echoed reply buffer from a short request UFID, then ovs_flow_cmd_fill_info() writes the longer key identifier found by fallback lookup. The path requires permission to issue flow updates; reaching BUG_ON after an EMSGSIZE failure crashes the kernel without reported data disclosure or modification.

The record

CVE
CVE-2026-74664
Published
Aug 22, 2026
Updated
Aug 22, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-131, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 22, 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=4.0
  2. Affected versionversion=74ed7ab9264c54471c7f057409d352052820d750 <00f987f066e802793a37dd2167459e67cf2cf2ec
  3. Affected versionversion=74ed7ab9264c54471c7f057409d352052820d750 <20751193d83be2e9735d4faee71375691c09cd13
  4. Affected versionversion=74ed7ab9264c54471c7f057409d352052820d750 <23716dd9d8d46a5908536b73dc085e62f2b5c237
  5. Affected versionversion=74ed7ab9264c54471c7f057409d352052820d750 <5d1c224dd914579524a183a514c12b95095d12ce
  6. Affected versionversion=74ed7ab9264c54471c7f057409d352052820d750 <696a0b9435fce9cf4f1e9ba7f6afa6bee96c97fc
  7. Affected versionversion=74ed7ab9264c54471c7f057409d352052820d750 <69f40ccf85074981340847d650a9cbf9adabfbbe
  8. Affected versionversion=74ed7ab9264c54471c7f057409d352052820d750 <87d0c0040b5d4b61de51ae39132c4c46709f2f77
  9. Affected versionversion=74ed7ab9264c54471c7f057409d352052820d750 <bd8ca84d48cd9a4f6fc63df26512c55e1d339927

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.0; version=74ed7ab9264c54471c7f057409d352052820d750 <00f987f066e802793a37dd2167459e67cf2cf2ec; version=74ed7ab9264c54471c7f057409d352052820d750 <20751193d83be2e9735d4faee71375691c09cd13; version=74ed7ab9264c54471c7f057409d352052820d750 <23716dd9d8d46a5908536b73dc085e62f2b5c237; version=74ed7ab9264c54471c7f057409d352052820d750 <5d1c224dd914579524a183a514c12b95095d12ce; version=74ed7ab9264c54471c7f057409d352052820d750 <696a0b9435fce9cf4f1e9ba7f6afa6bee96c97fc; version=74ed7ab9264c54471c7f057409d352052820d750 <69f40ccf85074981340847d650a9cbf9adabfbbe; version=74ed7ab9264c54471c7f057409d352052820d750 <87d0c0040b5d4b61de51ae39132c4c46709f2f77; version=74ed7ab9264c54471c7f057409d352052820d750 <bd8ca84d48cd9a4f6fc63df26512c55e1d339927

Published CVSS scores

5.5Oracle LinuxCVSS: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

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.

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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

CWE-131Incorrect Calculation of Buffer Size
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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