CVE-2026-99056Public exploit

Root escalation via receive-parser teardown race

Published Oct 23, 2026 · Updated Oct 23, 2026

A use-after-free in Linux espintcp allows local users to gain root privileges via a receive-parser teardown race. strp_done() cancels work without waiting for an active strp_recv(), allowing crafted partial frames to rearm msg_timer_work against freed espintcp_ctx memory. Exploitation requires ESP-in-TCP support and winning a timing-sensitive race; the published exploit requires no Linux capabilities and also supports a kernel-crash outcome.

CVSS severityUnavailable
Unscored
EPSS probability0.16%
Next 30 days · Nov 1, 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.

Contact us

Summary

What happened

A use-after-free in Linux espintcp allows local users to gain root privileges via a receive-parser teardown race. strp_done() cancels work without waiting for an active strp_recv(), allowing crafted partial frames to rearm msg_timer_work against freed espintcp_ctx memory. Exploitation requires ESP-in-TCP support and winning a timing-sensitive race; the published exploit requires no Linux capabilities and also supports a kernel-crash outcome.

The record

CVE
CVE-2026-99056
Published
Oct 23, 2026
Updated
Oct 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 23, 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=5.6
  2. Affected versionversion=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <0984ebc631792acf8fff105112ee74a6b8f1efcc
  3. Affected versionversion=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <9f3e9fe1b155e9b4572054d8d140586bc3512ecf
  4. Affected versionversion=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <a18dd388045dc7263d99a07db9de4e0f149ca8f1
  5. Affected versionversion=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <d2b5f637b9b67a79a50d42614d10653c13b4e449
  6. Affected versionversion=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <eaa3a29004c063d7e9d5ea55636f693f67e6db0f

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.6; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <0984ebc631792acf8fff105112ee74a6b8f1efcc; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <9f3e9fe1b155e9b4572054d8d140586bc3512ecf; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <a18dd388045dc7263d99a07db9de4e0f149ca8f1; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <d2b5f637b9b67a79a50d42614d10653c13b4e449; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <eaa3a29004c063d7e9d5ea55636f693f67e6db0f

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

Public exploit references

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

Get started to see how Hinoki identifies affected software and validates exploitability in your environment.

Contact us