{"id":"CVE-2026-72321","state":"PUBLISHED","title":"ipv4: igmp: Fix potential memory leaks in igmp_mod_timer() and igmp_stop_timer()","description":"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_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.","publishedAt":"2026-08-15T05:55:33.547Z","updatedAt":"2026-10-30T12:29:02.891Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"d4fe30f4671033a27fba077b3976dc113ffc0169","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"2d0effadf8d2cc9d006e4c4ab0ab6737aed28d77","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"40d6360ccf9bcbe17b5cb248a84e8e004aac2faa","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"f60ec3058a85447008b88b762c859d336163acb3","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"95128dc74425ec19ed4f2077ccc651e791ff4b75","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"3546deaa0c30a14c7cdb5dc8f2432cb428f0cd36","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/igmp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/igmp.c"]}],"references":["https://git.kernel.org/stable/c/d4fe30f4671033a27fba077b3976dc113ffc0169","https://git.kernel.org/stable/c/2d0effadf8d2cc9d006e4c4ab0ab6737aed28d77","https://git.kernel.org/stable/c/40d6360ccf9bcbe17b5cb248a84e8e004aac2faa","https://git.kernel.org/stable/c/f60ec3058a85447008b88b762c859d336163acb3","https://git.kernel.org/stable/c/95128dc74425ec19ed4f2077ccc651e791ff4b75","https://git.kernel.org/stable/c/3546deaa0c30a14c7cdb5dc8f2432cb428f0cd36"],"weaknesses":[],"ingestedAt":"2026-10-30T12:48:04.825Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72321.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72321","state":"PUBLISHED","datePublished":"2026-08-15T05:55:33.547Z","dateUpdated":"2026-10-30T12:29:02.891Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-09T03:40:39.919Z"},"containers":{"cna":{"title":"ipv4: igmp: Fix potential memory leaks in igmp_mod_timer() and igmp_stop_timer()","descriptions":[{"lang":"en","value":"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_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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"d4fe30f4671033a27fba077b3976dc113ffc0169","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"2d0effadf8d2cc9d006e4c4ab0ab6737aed28d77","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"40d6360ccf9bcbe17b5cb248a84e8e004aac2faa","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"f60ec3058a85447008b88b762c859d336163acb3","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"95128dc74425ec19ed4f2077ccc651e791ff4b75","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"3546deaa0c30a14c7cdb5dc8f2432cb428f0cd36","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/igmp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/igmp.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/d4fe30f4671033a27fba077b3976dc113ffc0169"},{"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"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:29:02.891Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}