# CVE-2026-72321: ipv4: igmp: Fix potential memory leaks in igmp_mod_timer() and igmp_stop_timer()

CVE-2026-72321 is fixed in 53 products on 1 platform, first by DEBIAN-CVE-2026-72321, released August 15, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-72321
- Priority: Routine
- CVSS: 3.1 (Low)
- EPSS: 0.0022
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 15, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-72321

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | bpftool6.12 amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | bpftool6.12-debuginfo amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | bpftool6.18 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | dtb-aarch64 opensuse-leap 16.0 | 6.12.0-160000.39.1 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-64kb opensuse-leap 16.0 | 6.12.0-160000.39.1 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-64kb sles 15.7 | 6.4.0-150700.53.84.1 | [SUSE-SU-2026:4706-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4706-1.md) | Nov 7, 2026 |
| Linux | kernel-64kb sles 16.0 | 6.12.0-160000.39.1 | [SUSE-SU-2026:24235-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24235-1.md) | Nov 7, 2026 |
| Linux | kernel-azure opensuse-leap 16.0 | 6.12.0-160000.39.1 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-azure sles 15.7 | 6.4.0-150700.53.84.1 | [SUSE-SU-2026:4706-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4706-1.md) | Nov 7, 2026 |
| Linux | kernel-azure sles 16.0 | 6.12.0-160000.39.1 | [SUSE-SU-2026:24235-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24235-1.md) | Nov 7, 2026 |
| Linux | kernel-default opensuse-leap 16.0 | 6.12.0-160000.39.1 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-default sles 15.7 | 6.4.0-150700.53.84.1 | [SUSE-SU-2026:4706-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4706-1.md) | Nov 7, 2026 |
| Linux | kernel-default sles 16.0 | 6.12.0-160000.39.1 | [SUSE-SU-2026:24197-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24197-1.md) | Nov 7, 2026 |
| Linux | kernel-default-base opensuse-leap 16.0 | 6.12.0-160000.39.1.160000.2.25 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-default-base sles 15.7 | 6.4.0-150700.53.84.1.150700.17.47.1 | [SUSE-SU-2026:4706-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4706-1.md) | Nov 7, 2026 |
| Linux | kernel-default-base sles 16.0 | 6.12.0-160000.39.1.160000.2.26 | [SUSE-SU-2026:24235-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24235-1.md) | Nov 7, 2026 |
| Linux | kernel-docs opensuse-leap 16.0 | 6.12.0-160000.39.1 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-docs sles 15.7 | 6.4.0-150700.53.84.1 | [SUSE-SU-2026:4706-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4706-1.md) | Nov 7, 2026 |
| Linux | kernel-docs sles 16.0 | 6.12.0-160000.39.1 | [SUSE-SU-2026:24235-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24235-1.md) | Nov 7, 2026 |
| Linux | kernel-kvmsmall opensuse-leap 16.0 | 6.12.0-160000.39.1 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-kvmsmall sles 16.0 | 6.12.0-160000.39.1 | [SUSE-SU-2026:24235-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24235-1.md) | Nov 7, 2026 |
| Linux | kernel-livepatch-6.12.114-139.210 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | kernel-livepatch-6.18.41-94.142 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | kernel-livepatch-SLE15-SP7-RT_Update_21 sles 15.7 | 1-150700.1.3.1 | [SUSE-SU-2026:4640-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4640-1.md) | Nov 7, 2026 |
| Linux | kernel-livepatch-SLE15-SP7_Update_22 sles 15.7 | 1-150700.15.3.1 | [SUSE-SU-2026:4706-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4706-1.md) | Nov 7, 2026 |
| Linux | kernel-obs-build opensuse-leap 16.0 | 6.12.0-160000.39.1 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-obs-build sles 15.7 | 6.4.0-150700.53.84.1 | [SUSE-SU-2026:4706-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4706-1.md) | Nov 7, 2026 |
| Linux | kernel-obs-qa opensuse-leap 16.0 | 6.12.0-160000.39.1 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-obs-qa sles 16.0 | 6.12.0-160000.39.1 | [SUSE-SU-2026:24235-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24235-1.md) | Nov 7, 2026 |
| Linux | kernel-rt opensuse-leap 16.0 | 6.12.0-160000.39.1 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-source opensuse-leap 16.0 | 6.12.0-160000.39.1 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-source sles 15.7 | 6.4.0-150700.53.84.1 | [SUSE-SU-2026:4706-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4706-1.md) | Nov 7, 2026 |
| Linux | kernel-source sles 16.0 | 6.12.0-160000.39.1 | [SUSE-SU-2026:24235-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24235-1.md) | Nov 7, 2026 |
| Linux | kernel-syms opensuse-leap 16.0 | 6.12.0-160000.39.1 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-syms sles 15.7 | 6.4.0-150700.53.84.1 | [SUSE-SU-2026:4706-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4706-1.md) | Nov 7, 2026 |
| Linux | kernel-syms sles 16.0 | 6.12.0-160000.39.1 | [SUSE-SU-2026:24235-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24235-1.md) | Nov 7, 2026 |
| Linux | kernel-zfcpdump opensuse-leap 16.0 | 6.12.0-160000.39.1 | [OPENSUSE-SU-2026:22091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22091-1.md) | Nov 7, 2026 |
| Linux | kernel-zfcpdump sles 15.7 | 6.4.0-150700.53.84.1 | [SUSE-SU-2026:4706-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4706-1.md) | Nov 7, 2026 |
| Linux | kernel-zfcpdump sles 16.0 | 6.12.0-160000.39.1 | [SUSE-SU-2026:24235-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24235-1.md) | Nov 7, 2026 |
| Linux | kernel6.12 amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | kernel6.12-debuginfo amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | kernel6.12-debuginfo-common-aarch64 amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | kernel6.12-debuginfo-common-x86_64 amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | kernel6.12-devel amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | kernel6.12-headers amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | kernel6.12-modules-extra amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | kernel6.12-modules-extra-common amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | kernel6.12-tools amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | kernel6.12-tools-debuginfo amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | kernel6.12-tools-devel amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | kernel6.18 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | kernel6.18-devel amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | kernel6.18-headers amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | kernel6.18-tools amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | linux Debian 13.5 (trixie) | 6.12.115-2 | [DEBIAN-CVE-2026-72321](https://patchblox.com/security/data/fix/linux/debian-cve-2026-72321.md) | Aug 15, 2026 |
| Linux | linux Debian 14 | 7.1.5-1 | [DEBIAN-CVE-2026-72321](https://patchblox.com/security/data/fix/linux/debian-cve-2026-72321.md) | Aug 15, 2026 |
| Linux | microvm-kernel6.18 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | perf6.12 amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | perf6.12-debuginfo amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | perf6.18 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | python3-perf6.12 amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | python3-perf6.12-debuginfo amzn 2023 | 1:6.12.114-139.210.amzn2023 | [ALAS2023-2026-3402](https://patchblox.com/security/data/fix/linux/alas2023-2026-3402.md) | Nov 10, 2026 |
| Linux | python3-perf6.18 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |
| Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 |

---

Data as of 2026-11-10T07:50:38Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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