CVE-2026-89487

Unprivileged page-cache writes via borrowed packet error handling

Published Sep 11, 2026 · Updated Sep 11, 2026

Improper packet error handling in Linux Open vSwitch allows local users to write to page-cache pages through ESP-in-UDP delivery. The queue_userspace_packet error path calls skb_tx_error on a borrowed live skb, clearing SKBFL_SHARED_FRAG before later actions continue forwarding it. Exploitation requires MSG_ZEROCOPY page-cache fragments, a failed USERSPACE upcall followed by another action, and local ESP-in-UDP delivery.

CVSS severityUnavailable
Unscored
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper packet error handling in Linux Open vSwitch allows local users to write to page-cache pages through ESP-in-UDP delivery. The queue_userspace_packet error path calls skb_tx_error on a borrowed live skb, clearing SKBFL_SHARED_FRAG before later actions continue forwarding it. Exploitation requires MSG_ZEROCOPY page-cache fragments, a failed USERSPACE upcall followed by another action, and local ESP-in-UDP delivery.

The record

CVE
CVE-2026-89487
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 11, 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=1674b4bf3eea3cac51b70778e89f8025f7cfe695
  2. Affected versionversion=3.10.51 <3.11
  3. Affected versionversion=3.12.40 <3.13
  4. Affected versionversion=3.14
  5. Affected versionversion=36d5fe6a000790f56039afe26834265db0a3ad4c <0dbc2398fca3bb33eda963849f865ddb1b3aa05e
  6. Affected versionversion=36d5fe6a000790f56039afe26834265db0a3ad4c <5d85eef222cfd28e73deed7402c100229e8b9e6e
  7. Affected versionversion=36d5fe6a000790f56039afe26834265db0a3ad4c <6767d70cf46f65807a6a4c4406a518e6c12e36ae
  8. Affected versionversion=36d5fe6a000790f56039afe26834265db0a3ad4c <e41a59fc056f63a7a1f42788913c53cc48d744aa
  9. Affected versionversion=c5f0c0e7525443add533495e93ba8de6feab2396

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1674b4bf3eea3cac51b70778e89f8025f7cfe695; version=3.10.51 <3.11; version=3.12.40 <3.13; version=3.14; version=36d5fe6a000790f56039afe26834265db0a3ad4c <0dbc2398fca3bb33eda963849f865ddb1b3aa05e; version=36d5fe6a000790f56039afe26834265db0a3ad4c <5d85eef222cfd28e73deed7402c100229e8b9e6e; version=36d5fe6a000790f56039afe26834265db0a3ad4c <6767d70cf46f65807a6a4c4406a518e6c12e36ae; version=36d5fe6a000790f56039afe26834265db0a3ad4c <e41a59fc056f63a7a1f42788913c53cc48d744aa; version=c5f0c0e7525443add533495e93ba8de6feab2396

Published CVSS scores

No CVSS assessment is available in this record.

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

T1068Exploitation for Privilege Escalation

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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