Linux Kernel up to 6.18.39/7.1.4/7.2-rc2 ipv4 igmp_mod_timer/igmp_stop_timer memory leak

CVSS Meta Temp Score
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CTI Interest Score
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7.0$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.18.39/7.1.4/7.2-rc2. The affected element is the function igmp_mod_timer/igmp_stop_timer of the component ipv4. The manipulation results in memory leak. This vulnerability is cataloged as CVE-2026-72321. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.18.39/7.1.4/7.2-rc2. Affected is the function igmp_mod_timer/igmp_stop_timer of the component ipv4. The manipulation with an unknown input leads to a memory leak vulnerability. CWE is classifying the issue as CWE-401. The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: ipv4: igmp: Fix potential memory leaks in igmp_mod_timer() and igmp_stop_timer() When a timer is deleted and not re-armed in igmp_mod_timer(), or stopped in igmp_stop_timer(), the code currently decrements the reference counter of the multicast list entry @im using refcount_dec(&im->refcnt). However, both functions can be called from the RCU reader path: - igmp_mod_timer() via igmp_heard_query() -> for_each_pmc_rcu() - igmp_stop_timer() via igmp_rcv() -> igmp_heard_report() If the group im was concurrently removed from the list by ip_mc_dec_group(), its reference count might have already been decremented to 1. In this case, timer_delete() succeeds, and refcount_dec() decrements the refcount from 1 to 0. Since refcount_dec() does not free the object when it hits 0 (unlike ip_ma_put()), the im structure is leaked. Fix this by using ip_ma_put(im) instead of refcount_dec(&im->refcnt), and deferring the put until after the spinlock is released.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-72321 since 08/09/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 08/15/2026). The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 6.18.40, 7.1.5 or 7.2-rc3 eliminates this vulnerability. Applying the patch f60ec3058a85447008b88b762c859d336163acb3/95128dc74425ec19ed4f2077ccc651e791ff4b75/3546deaa0c30a14c7cdb5dc8f2432cb428f0cd36 is able to eliminate this problem.

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Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Memory leak
CWE: CWE-401 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.40/7.1.5/7.2-rc3
Patch: f60ec3058a85447008b88b762c859d336163acb3/95128dc74425ec19ed4f2077ccc651e791ff4b75/3546deaa0c30a14c7cdb5dc8f2432cb428f0cd36

Timelineinfo

08/09/2026 CVE reserved
08/15/2026 +6 days Advisory disclosed
08/15/2026 +0 days VulDB entry created
08/15/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-72321 (🔒)
GCVE (CVE): GCVE-0-2026-72321
GCVE (VulDB): GCVE-100-390924

Entryinfo

Created: 08/15/2026 16:20
Changes: 08/15/2026 16:20 (59)
Complete: 🔍
Cache ID: 216::103

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