CVE-2026-31518

Local service interruption via asynchronous ESP skb leak

Published Apr 22, 2026 · Updated Apr 22, 2026

Memory leak in the Linux Kernel allows local users to exhaust kernel memory through ESP-in-TCP traffic using asynchronous crypto. When the transmit queue is full, esp_output_done passes an error from esp_output_tail_tcp without freeing the associated skb. Reaching the flaw requires low-privileged local access, ESP-in-TCP output, asynchronous crypto, and a full transmit queue; repeated failures interrupt service by depleting kernel memory.

CVSS severity5.5
Medium
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

Memory leak in the Linux Kernel allows local users to exhaust kernel memory through ESP-in-TCP traffic using asynchronous crypto. When the transmit queue is full, esp_output_done passes an error from esp_output_tail_tcp without freeing the associated skb. Reaching the flaw requires low-privileged local access, ESP-in-TCP output, asynchronous crypto, and a full transmit queue; repeated failures interrupt service by depleting kernel memory.

The record

CVE
CVE-2026-31518
Published
Apr 22, 2026
Updated
Apr 22, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 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 <0c0eef8ccd2413b0a10eb6bbd3442333b1e64dd2
  3. Affected versionversion=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <41aafca57de4a4c026701622bd4648f112a9edcd
  4. Affected versionversion=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <4820847e036ff1035b01b69ad68dfc17e7028fe9
  5. Affected versionversion=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <6a3ec6efbc4f90e0ccb2e71574f07351f19996f4
  6. Affected versionversion=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <6aa9841d917532d0f2d932d1ff2f3a94305aaf47
  7. Affected versionversion=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <88d386243ed374ac969dabd3bbc1409a31d81818
  8. Affected versionversion=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <aca3ad0c262f54a5b5c95dda80a48365997d1224
  9. Affected versionversion=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <df6f995358dc1f3c42484f5cfe241d7bd3e1cd15

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.6; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <0c0eef8ccd2413b0a10eb6bbd3442333b1e64dd2; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <41aafca57de4a4c026701622bd4648f112a9edcd; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <4820847e036ff1035b01b69ad68dfc17e7028fe9; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <6a3ec6efbc4f90e0ccb2e71574f07351f19996f4; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <6aa9841d917532d0f2d932d1ff2f3a94305aaf47; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <88d386243ed374ac969dabd3bbc1409a31d81818; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <aca3ad0c262f54a5b5c95dda80a48365997d1224; version=e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 <df6f995358dc1f3c42484f5cfe241d7bd3e1cd15

Published CVSS scores

5.5UbuntuCVSS: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.

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

T1499.001Endpoint Denial of Service: OS Exhaustion Flood

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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