CVE-2026-98549Hinoki check available

Disclosure or hangs via cross-encryption buffer merging

Published Oct 18, 2026 · Updated Oct 18, 2026

TCP buffer merging in Linux before 7.3-rc5 allows attackers to read PSP traffic or hang TLS-offloaded connections on retransmission. tcp_write_collapse_fence() leaves outstanding retransmission buffers unfenced when the write queue is empty, allowing later data to merge across the device-encryption boundary. Exposure requires an encryption transition with earlier data still unacknowledged: PSP retransmits merged data in cleartext, while TLS device offload repeatedly drops the merged buffer and stalls the connection.

CVSS severityUnavailable
Unscored
EPSS probability0.13%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

TCP buffer merging in Linux before 7.3-rc5 allows attackers to read PSP traffic or hang TLS-offloaded connections on retransmission. tcp_write_collapse_fence() leaves outstanding retransmission buffers unfenced when the write queue is empty, allowing later data to merge across the device-encryption boundary. Exposure requires an encryption transition with earlier data still unacknowledged: PSP retransmits merged data in cleartext, while TLS device offload repeatedly drops the merged buffer and stalls the connection.

The record

CVE
CVE-2026-98549
Published
Oct 18, 2026
Updated
Oct 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 18, 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=4.18
  2. Affected versionversion=e8f69799810c32dd40c6724d829eccc70baad07f <08e835f5ec6e261c79d8c39f8618b3af29e3b0da
  3. Affected versionversion=e8f69799810c32dd40c6724d829eccc70baad07f <1ae7aee395245874d797890380d9192bd858fb7e
  4. Affected versionversion=e8f69799810c32dd40c6724d829eccc70baad07f <7ba87509c54cd519e7ed362e0c85e8431f066a18
  5. Affected versionversion=e8f69799810c32dd40c6724d829eccc70baad07f <fc6d80eb504458d6416b75a94188b268c95c6533

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=4.18; version=e8f69799810c32dd40c6724d829eccc70baad07f <08e835f5ec6e261c79d8c39f8618b3af29e3b0da; version=e8f69799810c32dd40c6724d829eccc70baad07f <1ae7aee395245874d797890380d9192bd858fb7e; version=e8f69799810c32dd40c6724d829eccc70baad07f <7ba87509c54cd519e7ed362e0c85e8431f066a18; version=e8f69799810c32dd40c6724d829eccc70baad07f <fc6d80eb504458d6416b75a94188b268c95c6533

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.

Activity data is delayed. The latest report is Sep 28, 2026.

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No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

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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