{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-80842", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-80842", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-09-04T15:54:52.459Z", "updatedAt": "2026-10-19T08:44:35.389Z", "importedAt": "2026-10-24T01:58:30.346Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "net: bridge: mcast: fix use-after-free of a master VLAN's multicast context", "summary": "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": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "status": "affected", "versionType": "git", "lessThan": "3afaaee2f972aec9059110953adb62fa3cf5c4bd" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "status": "affected", "versionType": "git", "lessThan": "22226a2c3b90f15b0925f1464470d3baa6c5677e" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "status": "affected", "versionType": "git", "lessThan": "7c54fd8cfbcf371a5ef50db5c53fe6e85fb76686" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "status": "affected", "versionType": "git", "lessThan": "3a0ad4fcdfa0b7dba1876de14a12cb65c8b5ca50" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "status": "affected", "versionType": "git", "lessThan": "c069f29da72324697aa4b7cab5b3647a7d24a575" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "status": "affected", "versionType": "git", "lessThan": "3f4752996735e0628af559aa8da1d872c2fac13b" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "status": "affected", "versionType": "git", "lessThan": "57f94d3f4dee8b54d63cefddf1112be4656ef9e6" }, { "version": "7b54aaaf53cb784411426c64482af0435f7c845e", "status": "affected", "versionType": "git", "lessThan": "50e5c6605cc9c2dd57bd2d1b3459674d19738983" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "5.15", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "5.15" }, { "version": "5.15.220", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.187", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.156", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.108", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.49", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.1.13", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.1.*" }, { "version": "7.2.3", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.2.*" }, { "version": "7.3", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }