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.
History

Sat, 22 Aug 2026 07:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-401

Wed, 19 Aug 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-911
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Low


Sat, 15 Aug 2026 10:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-401

Sat, 15 Aug 2026 06:00:00 +0000

Type Values Removed Values Added
Description 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.
Title ipv4: igmp: Fix potential memory leaks in igmp_mod_timer() and igmp_stop_timer()
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-08-15T05:55:33.547Z

Updated: 2026-08-17T05:12:27.313Z

Reserved: 2026-08-09T03:40:39.919Z

Link: CVE-2026-72321

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-15T06:22:05.103

Modified: 2026-08-17T06:18:35.587

Link: CVE-2026-72321

cve-icon Redhat

Severity : Low

Publid Date: 2026-08-15T00:00:00Z

Links: CVE-2026-72321 - Bugzilla