CVE-2026-23247Network attack vector

TCP source-port disclosure via per-host timestamp offsets

Published Mar 18, 2026 · Updated Mar 18, 2026

Information disclosure in the Linux kernel allows remote attackers to infer TCP source ports through a SYN-cookie side channel. The secure_tcp_ts_off path hashes only the source and destination addresses, so different port pairs reuse a per-host TCP timestamp offset. The leak requires TCP timestamps and a SYN-cookie exchange; it exposes port information without granting data modification or code execution.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in the Linux kernel allows remote attackers to infer TCP source ports through a SYN-cookie side channel. The secure_tcp_ts_off path hashes only the source and destination addresses, so different port pairs reuse a per-host TCP timestamp offset. The leak requires TCP timestamps and a SYN-cookie exchange; it exposes port information without granting data modification or code execution.

The record

CVE
CVE-2026-23247
Published
Mar 18, 2026
Updated
Mar 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 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=28ee1b746f493b7c62347d714f58fbf4f70df4f0 <165573e41f2f66ef98940cf65f838b2cb575d9d1
  2. Affected versionversion=28ee1b746f493b7c62347d714f58fbf4f70df4f0 <46e5b0d7cf55821527adea471ffe52a5afbd9caf
  3. Affected versionversion=28ee1b746f493b7c62347d714f58fbf4f70df4f0 <eae2f14ab2efccdb7480fae7d42c4b0116ef8805
  4. Affected versionversion=4.11
  5. Affected versionversion=443fac9f2618b93cbc5ab068dc594530236b3a23

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=28ee1b746f493b7c62347d714f58fbf4f70df4f0 <165573e41f2f66ef98940cf65f838b2cb575d9d1; version=28ee1b746f493b7c62347d714f58fbf4f70df4f0 <46e5b0d7cf55821527adea471ffe52a5afbd9caf; version=28ee1b746f493b7c62347d714f58fbf4f70df4f0 <eae2f14ab2efccdb7480fae7d42c4b0116ef8805; version=4.11; version=443fac9f2618b93cbc5ab068dc594530236b3a23

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Canonical UbuntuCVSS: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)
Vectornetwork
Privilegesunauthenticated
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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