CVE-2026-23240Network attack vector

Use-after-free via rescheduled TLS transmit work

Published Mar 10, 2026 · Updated Mar 10, 2026

Use-after-free in Linux kernel TLS software transmit handling allows remote attackers to trigger a freed-object dereference through a race. tls_sw_cancel_work_tx() cancels delayed transmit work without disabling it, so tls_sw_write_space() can schedule tx_work_handler() after TLS teardown frees its object. The race requires socket teardown to overlap a write-space callback; the public record does not establish a reproducible crash or code-execution outcome.

CVSS severity9.8
Critical
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Use-after-free in Linux kernel TLS software transmit handling allows remote attackers to trigger a freed-object dereference through a race. tls_sw_cancel_work_tx() cancels delayed transmit work without disabling it, so tls_sw_write_space() can schedule tx_work_handler() after TLS teardown frees its object. The race requires socket teardown to overlap a write-space callback; the public record does not establish a reproducible crash or code-execution outcome.

The record

CVE
CVE-2026-23240
Published
Mar 10, 2026
Updated
Mar 10, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-362
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 10, 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=5.3
  2. Affected versionversion=f87e62d45e51b12d48d2cb46b5cde8f83b866bc4 <17153f154f80be2b47ebf52840f2d8f724eb2f3b
  3. Affected versionversion=f87e62d45e51b12d48d2cb46b5cde8f83b866bc4 <7bb09315f93dce6acc54bf59e5a95ba7365c2be4
  4. Affected versionversion=f87e62d45e51b12d48d2cb46b5cde8f83b866bc4 <854cd32bc74fe573353095e90958490e4e4d641b
  5. Affected versionversion=f87e62d45e51b12d48d2cb46b5cde8f83b866bc4 <a5de36d6cee74a92c1a21b260bc507e64bc451de

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.3; version=f87e62d45e51b12d48d2cb46b5cde8f83b866bc4 <17153f154f80be2b47ebf52840f2d8f724eb2f3b; version=f87e62d45e51b12d48d2cb46b5cde8f83b866bc4 <7bb09315f93dce6acc54bf59e5a95ba7365c2be4; version=f87e62d45e51b12d48d2cb46b5cde8f83b866bc4 <854cd32bc74fe573353095e90958490e4e4d641b; version=f87e62d45e51b12d48d2cb46b5cde8f83b866bc4 <a5de36d6cee74a92c1a21b260bc507e64bc451de

Published CVSS scores

9.8LinuxCVSS:3.1/AV:N/AC:L/PR:N/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-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo