CVE-2026-72321

Service degradation via leaked multicast entries

Published Aug 15, 2026 · Updated Aug 15, 2026

Memory leak in Linux kernel IPv4 IGMP handling allows local users to degrade system stability through multicast timer races. igmp_mod_timer() and igmp_stop_timer() call refcount_dec() after timer deletion, so a concurrently removed multicast entry can reach zero without ip_ma_put() freeing its im structure. Triggering the flaw requires local low-privileged access and a race with group removal; repeated leaks consume kernel memory and can interrupt service.

CVSS severity5.5
Medium
EPSS probability0.21%
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 Linux kernel IPv4 IGMP handling allows local users to degrade system stability through multicast timer races. igmp_mod_timer() and igmp_stop_timer() call refcount_dec() after timer deletion, so a concurrently removed multicast entry can reach zero without ip_ma_put() freeing its im structure. Triggering the flaw requires local low-privileged access and a race with group removal; repeated leaks consume kernel memory and can interrupt service.

The record

CVE
CVE-2026-72321
Published
Aug 15, 2026
Updated
Aug 15, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-911, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 15, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3546deaa0c30a14c7cdb5dc8f2432cb428f0cd36
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <95128dc74425ec19ed4f2077ccc651e791ff4b75
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f60ec3058a85447008b88b762c859d336163acb3
  4. Affected versionversion=2.6.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3546deaa0c30a14c7cdb5dc8f2432cb428f0cd36; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <95128dc74425ec19ed4f2077ccc651e791ff4b75; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f60ec3058a85447008b88b762c859d336163acb3; version=2.6.12

Published CVSS scores

5.5Red HatCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.7Amazon LinuxCVSS:3.1/AV:L/AC:H/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-911Improper Update of Reference Count
T1499.004Application or System Exploitation

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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