{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-80842", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-26T14:34:25.796Z", "datePublished": "2026-09-04T15:54:52.459Z", "dateUpdated": "2026-10-19T08:44:35.389Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:44:35.389Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: mcast: fix use-after-free of a master VLAN's multicast context\n\nbr_multicast_toggle_one_vlan() clears BR_VLFLAG_MCAST_ENABLED under\nbr->multicast_lock before stopping a VLAN's multicast context. That is\nthe teardown handshake: lockless readers gate on the flag through\nbr_multicast_ctx_should_use() -> br_multicast_ctx_vlan_disabled(), so\nonce it is cleared under the lock no reader can arm the context again.\n\nFor a master VLAN the handshake never runs. __vlan_del() clears\nBRIDGE_VLAN_INFO_BRENTRY before calling br_vlan_put_master(), so\nbr_multicast_toggle_one_vlan(masterv, false) returns early on\n!br_vlan_is_brentry(vlan): the flag stays set and br->multicast_lock is\nnever taken. br_vlan_put_master() then drains the context in\nbr_multicast_ctx_deinit() and frees the VLAN through call_rcu(), while a\nreader still inside rcu_read_lock() sees the context as enabled and\nre-arms it. The port and port-VLAN branch of the function has no\nbr_vlan_is_brentry() test and flips the flag under br->multicast_lock,\nso it is not affected.\n\nThe reader is the bridge transmit path. For a master VLAN\nbr_multicast_rcv() selects brmctx = &vlan->br_mcast_ctx with\npmctx = NULL, so IGMP sent to the bridge device re-arms the context's\ntimers after br_multicast_ctx_deinit() has already stopped them.\n\n BUG: KASAN: slab-use-after-free in detach_if_pending+0x412/0x4a0\n Write of size 8 at addr ffff88810ac39918 by task brmc/601\n __mod_timer+0x51a/0xc50\n br_multicast_host_join+0x25b/0x390\n __br_multicast_add_group+0x468/0x530\n br_ip4_multicast_add_group+0x1a0/0x260\n br_multicast_rcv+0x2cda/0x61e0\n br_dev_xmit+0x6c4/0x1540\n Allocated by task 610:\n br_vlan_add+0x111/0xb40\n br_vlan_info+0x370/0x3e0\n Freed by task 0:\n kfree+0x1a7/0x4f0\n rcu_core+0x7dc/0x10a0\n\nOnly test br_vlan_is_brentry() when enabling, like the\nbr_multicast_ctx_vlan_global_disabled() test next to it. Disabling then\nalways clears BR_VLFLAG_MCAST_ENABLED under br->multicast_lock before\nbr_multicast_ctx_deinit() drains the context." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bridge/br_multicast.c" ], "versions": [ { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "lessThan": "3afaaee2f972aec9059110953adb62fa3cf5c4bd", "status": "affected", "versionType": "git" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "lessThan": "22226a2c3b90f15b0925f1464470d3baa6c5677e", "status": "affected", "versionType": "git" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "lessThan": "7c54fd8cfbcf371a5ef50db5c53fe6e85fb76686", "status": "affected", "versionType": "git" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "lessThan": "3a0ad4fcdfa0b7dba1876de14a12cb65c8b5ca50", "status": "affected", "versionType": "git" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "lessThan": "c069f29da72324697aa4b7cab5b3647a7d24a575", "status": "affected", "versionType": "git" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "lessThan": "3f4752996735e0628af559aa8da1d872c2fac13b", "status": "affected", "versionType": "git" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "lessThan": "57f94d3f4dee8b54d63cefddf1112be4656ef9e6", "status": "affected", "versionType": "git" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "lessThan": "50e5c6605cc9c2dd57bd2d1b3459674d19738983", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bridge/br_multicast.c" ], "versions": [ { "version": "5.15", "status": "affected" }, { "version": "0", "lessThan": "5.15", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.220", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.187", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.156", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.108", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.49", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.13", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.3", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "5.15.220" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.1.187" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.6.156" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.12.108" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.18.49" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.1.13" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.2.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3afaaee2f972aec9059110953adb62fa3cf5c4bd" }, { "url": "https://git.kernel.org/stable/c/22226a2c3b90f15b0925f1464470d3baa6c5677e" }, { "url": "https://git.kernel.org/stable/c/7c54fd8cfbcf371a5ef50db5c53fe6e85fb76686" }, { "url": "https://git.kernel.org/stable/c/3a0ad4fcdfa0b7dba1876de14a12cb65c8b5ca50" }, { "url": "https://git.kernel.org/stable/c/c069f29da72324697aa4b7cab5b3647a7d24a575" }, { "url": "https://git.kernel.org/stable/c/3f4752996735e0628af559aa8da1d872c2fac13b" }, { "url": "https://git.kernel.org/stable/c/57f94d3f4dee8b54d63cefddf1112be4656ef9e6" }, { "url": "https://git.kernel.org/stable/c/50e5c6605cc9c2dd57bd2d1b3459674d19738983" } ], "title": "net: bridge: mcast: fix use-after-free of a master VLAN's multicast context", "x_generator": { "engine": "bippy-1.2.0" } } } }