{"id":"CVE-2026-72321","title":"ipv4: igmp: Fix potential memory leaks in igmp_mod_timer() and igmp_stop_timer()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: igmp: Fix potential memory leaks in igmp_mod_timer() and igmp_stop_timer()\n\nWhen a timer is deleted and not re-armed in igmp_mod_timer(), or stopped\nin igmp_stop_…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 2d0effadf8d2cc9d006e4c4ab0ab6737aed28d77","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 40d6360ccf9bcbe17b5cb248a84e8e004aac2faa","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f60ec3058a85447008b88b762c859d336163acb3","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 95128dc74425ec19ed4f2077ccc651e791ff4b75","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 3546deaa0c30a14c7cdb5dc8f2432cb428f0cd36","Linux 2.6.12"],"published":"2026-08-15","updated":"2026-10-21","sourceUpdated":"2026-10-21T12:44:32.954Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72321","references":[{"url":"https://git.kernel.org/stable/c/2d0effadf8d2cc9d006e4c4ab0ab6737aed28d77"},{"url":"https://git.kernel.org/stable/c/40d6360ccf9bcbe17b5cb248a84e8e004aac2faa"},{"url":"https://git.kernel.org/stable/c/f60ec3058a85447008b88b762c859d336163acb3"},{"url":"https://git.kernel.org/stable/c/95128dc74425ec19ed4f2077ccc651e791ff4b75"},{"url":"https://git.kernel.org/stable/c/3546deaa0c30a14c7cdb5dc8f2432cb428f0cd36"}],"tags":["cve.org"],"epss":0.00207,"epssPercentile":0.10167,"ingestedAt":"2026-10-21T12:48:53.593Z","slug":"CVE-2026-72321","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nipv4: igmp: Fix potential memory leaks in igmp_mod_timer() and igmp_stop_timer()\n\nWhen a timer is deleted and not re-armed in igmp_mod_timer(), or stopped\nin igmp_stop_timer(), the code currently decrements the reference counter\nof the multicast list entry @im using refcount_dec(&im->refcnt).\n\nHowever, both functions can be called from the RCU reader path:\n- igmp_mod_timer() via igmp_heard_query() -> for_each_pmc_rcu()\n- igmp_stop_timer() via igmp_rcv() -> igmp_heard_report()\n\nIf the group im was concurrently removed from the list by ip_mc_dec_group(),\nits reference count might have already been decremented to 1.\n\nIn this case, timer_delete() succeeds, and refcount_dec() decrements\nthe refcount from 1 to 0. Since refcount_dec() does not free the object\nwhen it hits 0 (unlike ip_ma_put()), the im structure is leaked.\n\nFix this by using ip_ma_put(im) instead of refcount_dec(&im->refcnt),\nand deferring the put until after the spinlock is released.\n\n## Affected\n\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 2d0effadf8d2cc9d006e4c4ab0ab6737aed28d77`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 40d6360ccf9bcbe17b5cb248a84e8e004aac2faa`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f60ec3058a85447008b88b762c859d336163acb3`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 95128dc74425ec19ed4f2077ccc651e791ff4b75`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 3546deaa0c30a14c7cdb5dc8f2432cb428f0cd36`\n- `Linux 2.6.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}