In the Linux kernel, the following vulnerability has been resolved: net: bridge: mcast: fix use-after-free of a master VLAN's multicast context br_multicast_toggle_one_vlan() clears BR_VLFLAG_MCAST_ENABLED under br->multicast_lock before stopping a VLAN's multicast context. That is the teardown handshake: lockless readers gate on the flag through br_multicast_ctx_should_use() -> br_multicast_ctx_vlan_disabled(), so once it is cleared under the lock no reader can arm the context again. For a master VLAN the handshake never runs. __vlan_del() clears BRIDGE_VLAN_INFO_BRENTRY before calling br_vlan_put_master(), so br_multicast_toggle_one_vlan(masterv, false) returns early on !br_vlan_is_brentry(vlan): the flag stays set and br->multicast_lock is never taken. br_vlan_put_master() then drains the context in br_multicast_ctx_deinit() and frees the VLAN through call_rcu(), while a reader still inside rcu_read_lock() sees the context as enabled and re-arms it. The port and port-VLAN branch of the function has no br_vlan_is_brentry() test and flips the flag under br->multicast_lock, so it is not affected. The reader is the bridge transmit path. For a master VLAN br_multicast_rcv() selects brmctx = &vlan->br_mcast_ctx with pmctx = NULL, so IGMP sent to the bridge device re-arms the context's timers after br_multicast_ctx_deinit() has already stopped them. BUG: KASAN: slab-use-after-free in detach_if_pending+0x412/0x4a0 Write of size 8 at addr ffff88810ac39918 by task brmc/601 __mod_timer+0x51a/0xc50 br_multicast_host_join+0x25b/0x390 __br_multicast_add_group+0x468/0x530 br_ip4_multicast_add_group+0x1a0/0x260 br_multicast_rcv+0x2cda/0x61e0 br_dev_xmit+0x6c4/0x1540 Allocated by task 610: br_vlan_add+0x111/0xb40 br_vlan_info+0x370/0x3e0 Freed by task 0: kfree+0x1a7/0x4f0 rcu_core+0x7dc/0x10a0 Only test br_vlan_is_brentry() when enabling, like the br_multicast_ctx_vlan_global_disabled() test next to it. Disabling then always clears BR_VLFLAG_MCAST_ENABLED under br->multicast_lock before br_multicast_ctx_deinit() drains the context.

The remote Debian 12 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-4777 advisory.

    - -------------------------------------------------------------------------     Debian LTS Advisory DLA-4777-1                debian-lts@lists.debian.org     https://www.debian.org/lts/security/                 Salvatore Bonaccorso     September 08, 2026                            https://wiki.debian.org/LTS
    - -------------------------------------------------------------------------

    Package        : linux     Version        : 6.1.187-1     CVE ID         : CVE-2023-53706 CVE-2023-54141 CVE-2023-54263 CVE-2024-38620                      CVE-2024-46754 CVE-2024-58094 CVE-2024-58095 CVE-2025-22104                      CVE-2025-38117 CVE-2025-38203 CVE-2025-38206 CVE-2025-38237                      CVE-2025-38616 CVE-2025-39833 CVE-2025-39901 CVE-2025-39925                      CVE-2025-40054 CVE-2025-40064 CVE-2025-40102 CVE-2025-40139                      CVE-2025-40168 CVE-2025-40206 CVE-2025-40307 CVE-2025-68794                      CVE-2026-23394 CVE-2026-31419 CVE-2026-43491 CVE-2026-45963                      CVE-2026-46111 CVE-2026-46158 CVE-2026-46170 CVE-2026-46266                      CVE-2026-53089 CVE-2026-53090 CVE-2026-53361 CVE-2026-64082                      CVE-2026-64139 CVE-2026-64192 CVE-2026-64270 CVE-2026-64272                      CVE-2026-64280 CVE-2026-64294 CVE-2026-64434 CVE-2026-64507                      CVE-2026-64508 CVE-2026-64542 CVE-2026-64543 CVE-2026-64561                      CVE-2026-64562 CVE-2026-64563 CVE-2026-64564 CVE-2026-64565                      CVE-2026-64567 CVE-2026-64569 CVE-2026-64571 CVE-2026-64572                      CVE-2026-64573 CVE-2026-64576 CVE-2026-64577 CVE-2026-64578                      CVE-2026-64579 CVE-2026-64580 CVE-2026-64581 CVE-2026-64582                      CVE-2026-64583 CVE-2026-64584 CVE-2026-64586 CVE-2026-64590                      CVE-2026-68082 CVE-2026-68093 CVE-2026-68096 CVE-2026-68099                      CVE-2026-68100 CVE-2026-68104 CVE-2026-68106 CVE-2026-68108                      CVE-2026-68111 CVE-2026-68115 CVE-2026-68117 CVE-2026-68121                      CVE-2026-68123 CVE-2026-68124 CVE-2026-68125 CVE-2026-68127                      CVE-2026-68129 CVE-2026-68130 CVE-2026-68131 CVE-2026-68132                      CVE-2026-68135 CVE-2026-68136 CVE-2026-68137 CVE-2026-68138                      CVE-2026-68140 CVE-2026-68141 CVE-2026-68142 CVE-2026-68143                      CVE-2026-68144 CVE-2026-68146 CVE-2026-68147 CVE-2026-68148                      CVE-2026-68151 CVE-2026-68153 CVE-2026-68154 CVE-2026-68155                      CVE-2026-68156 CVE-2026-68157 CVE-2026-68158 CVE-2026-68159                      CVE-2026-68160 CVE-2026-68162 CVE-2026-68164 CVE-2026-68165                      CVE-2026-68169 CVE-2026-68175 CVE-2026-68176 CVE-2026-68180                      CVE-2026-68181 CVE-2026-68182 CVE-2026-68183 CVE-2026-68184                      CVE-2026-68186 CVE-2026-68187 CVE-2026-68188 CVE-2026-68189                      CVE-2026-68190 CVE-2026-68192 CVE-2026-68194 CVE-2026-68195                      CVE-2026-68196 CVE-2026-68197 CVE-2026-68198 CVE-2026-68199                      CVE-2026-68202 CVE-2026-68204 CVE-2026-68206 CVE-2026-68207                      CVE-2026-68209 CVE-2026-68210 CVE-2026-68212 CVE-2026-68213                      CVE-2026-68214 CVE-2026-68215 CVE-2026-68216 CVE-2026-68217                      CVE-2026-68218 CVE-2026-68222 CVE-2026-68223 CVE-2026-68226                      CVE-2026-68227 CVE-2026-68229 CVE-2026-68231 CVE-2026-68234                      CVE-2026-68243 CVE-2026-68244 CVE-2026-68246 CVE-2026-68248                      CVE-2026-68249 CVE-2026-68250 CVE-2026-68251 CVE-2026-68253                      CVE-2026-68254 CVE-2026-68255 CVE-2026-68259 CVE-2026-68269                      CVE-2026-68277 CVE-2026-68278 CVE-2026-68279 CVE-2026-68280                      CVE-2026-68284 CVE-2026-68294 CVE-2026-68297 CVE-2026-68299                      CVE-2026-68300 CVE-2026-68301 CVE-2026-68302 CVE-2026-68304                      CVE-2026-68309 CVE-2026-68310 CVE-2026-68313 CVE-2026-68315                      CVE-2026-68320 CVE-2026-68322 CVE-2026-68324 CVE-2026-68325                      CVE-2026-68326 CVE-2026-68327 CVE-2026-68328 CVE-2026-68331                      CVE-2026-68333 CVE-2026-68335 CVE-2026-68336 CVE-2026-68338                      CVE-2026-68340 CVE-2026-68343 CVE-2026-68344 CVE-2026-68349                      CVE-2026-68350 CVE-2026-68351 CVE-2026-68352 CVE-2026-68353                      CVE-2026-68354 CVE-2026-68355 CVE-2026-68357 CVE-2026-68359                      CVE-2026-68360 CVE-2026-68361 CVE-2026-68362 CVE-2026-68363                      CVE-2026-68365 CVE-2026-68366 CVE-2026-68367 CVE-2026-68368                      CVE-2026-68369 CVE-2026-68370 CVE-2026-68371 CVE-2026-68373                      CVE-2026-68376 CVE-2026-68377 CVE-2026-68386 CVE-2026-68388                      CVE-2026-68395 CVE-2026-68397 CVE-2026-68398 CVE-2026-68402                      CVE-2026-68403 CVE-2026-68405 CVE-2026-68406 CVE-2026-68407                      CVE-2026-68410 CVE-2026-68411 CVE-2026-68413 CVE-2026-68414                      CVE-2026-68417 CVE-2026-68422 CVE-2026-68425 CVE-2026-68427                      CVE-2026-68428 CVE-2026-68430 CVE-2026-68431 CVE-2026-68432                      CVE-2026-68433 CVE-2026-68434 CVE-2026-68444 CVE-2026-68446                      CVE-2026-68450 CVE-2026-68451 CVE-2026-68452 CVE-2026-68476                      CVE-2026-68480 CVE-2026-72012 CVE-2026-72015 CVE-2026-72017                      CVE-2026-72023 CVE-2026-72030 CVE-2026-72035 CVE-2026-72040                      CVE-2026-72041 CVE-2026-72045 CVE-2026-72051 CVE-2026-72057                      CVE-2026-72062 CVE-2026-72063 CVE-2026-72065 CVE-2026-72069                      CVE-2026-72070 CVE-2026-72077 CVE-2026-72096 CVE-2026-72099                      CVE-2026-72110 CVE-2026-72113 CVE-2026-72114 CVE-2026-72115                      CVE-2026-72116 CVE-2026-72117 CVE-2026-72118 CVE-2026-72119                      CVE-2026-72121 CVE-2026-72124 CVE-2026-72125 CVE-2026-72142                      CVE-2026-72146 CVE-2026-72157 CVE-2026-72170 CVE-2026-72172                      CVE-2026-72191 CVE-2026-72216 CVE-2026-72236 CVE-2026-72237                      CVE-2026-72242 CVE-2026-72252 CVE-2026-72253 CVE-2026-72260                      CVE-2026-72262 CVE-2026-72299 CVE-2026-72305 CVE-2026-72308                      CVE-2026-72323 CVE-2026-72392 CVE-2026-74436 CVE-2026-74441                      CVE-2026-74443 CVE-2026-74444 CVE-2026-74446 CVE-2026-74450                      CVE-2026-74453 CVE-2026-74454 CVE-2026-74455 CVE-2026-74456                      CVE-2026-74457 CVE-2026-74458 CVE-2026-74459 CVE-2026-74460                      CVE-2026-74461 CVE-2026-74463 CVE-2026-74464 CVE-2026-74465                      CVE-2026-74467 CVE-2026-74468 CVE-2026-74469 CVE-2026-74470                      CVE-2026-74471 CVE-2026-74472 CVE-2026-74473 CVE-2026-74475                      CVE-2026-74476 CVE-2026-74478 CVE-2026-74479 CVE-2026-74480                      CVE-2026-74481 CVE-2026-74482 CVE-2026-74485 CVE-2026-74487                      CVE-2026-74488 CVE-2026-74490 CVE-2026-74492 CVE-2026-74493                      CVE-2026-74494 CVE-2026-74495 CVE-2026-74497 CVE-2026-74498                      CVE-2026-74499 CVE-2026-74505 CVE-2026-74507 CVE-2026-74508                      CVE-2026-74509 CVE-2026-74510 CVE-2026-74512 CVE-2026-74514                      CVE-2026-74515 CVE-2026-74516 CVE-2026-74518 CVE-2026-74519                      CVE-2026-74522 CVE-2026-74523 CVE-2026-74525 CVE-2026-74540                      CVE-2026-74546 CVE-2026-74547 CVE-2026-74548 CVE-2026-74549                      CVE-2026-74550 CVE-2026-74551 CVE-2026-74552 CVE-2026-74553                      CVE-2026-74555 CVE-2026-74556 CVE-2026-74557 CVE-2026-74563                      CVE-2026-74564 CVE-2026-74566 CVE-2026-74567 CVE-2026-74569                      CVE-2026-74575 CVE-2026-74577 CVE-2026-74579 CVE-2026-74580                      CVE-2026-74581 CVE-2026-74582 CVE-2026-74583 CVE-2026-74585                      CVE-2026-74586 CVE-2026-74587 CVE-2026-74588 CVE-2026-74589                      CVE-2026-74594 CVE-2026-74595 CVE-2026-74597 CVE-2026-74598                      CVE-2026-74601 CVE-2026-74603 CVE-2026-74604 CVE-2026-74607                      CVE-2026-74608 CVE-2026-74609 CVE-2026-74612 CVE-2026-74613                      CVE-2026-74614 CVE-2026-74615 CVE-2026-74616 CVE-2026-74620                      CVE-2026-74621 CVE-2026-74622 CVE-2026-74623 CVE-2026-74624                      CVE-2026-74625 CVE-2026-74626 CVE-2026-74628 CVE-2026-74630                      CVE-2026-74631 CVE-2026-74632 CVE-2026-74635 CVE-2026-74636                      CVE-2026-74637 CVE-2026-74641 CVE-2026-74647 CVE-2026-74648                      CVE-2026-74649 CVE-2026-74650 CVE-2026-74651 CVE-2026-74654                      CVE-2026-74656 CVE-2026-74657 CVE-2026-74658 CVE-2026-74659                      CVE-2026-74660 CVE-2026-74662 CVE-2026-74663 CVE-2026-74664                      CVE-2026-74666 CVE-2026-74667 CVE-2026-74668 CVE-2026-74669                      CVE-2026-74671 CVE-2026-74672 CVE-2026-74673 CVE-2026-74675                      CVE-2026-74676 CVE-2026-74678 CVE-2026-74679 CVE-2026-74680                      CVE-2026-74682 CVE-2026-74683 CVE-2026-74688 CVE-2026-74689                      CVE-2026-74691 CVE-2026-74692 CVE-2026-74693 CVE-2026-74694                      CVE-2026-74696 CVE-2026-74697 CVE-2026-74701 CVE-2026-74704                      CVE-2026-74705 CVE-2026-74714 CVE-2026-74717 CVE-2026-74719                      CVE-2026-74720 CVE-2026-74722 CVE-2026-74724 CVE-2026-74726                      CVE-2026-74730 CVE-2026-74737 CVE-2026-74739 CVE-2026-74743                      CVE-2026-74744 CVE-2026-74746 CVE-2026-74748 CVE-2026-80527                      CVE-2026-80528 CVE-2026-80529 CVE-2026-80534 CVE-2026-80536                      CVE-2026-80539 CVE-2026-80540 CVE-2026-80541 CVE-2026-80547                      CVE-2026-80548 CVE-2026-80549 CVE-2026-80550 CVE-2026-80552                      CVE-2026-80553 CVE-2026-80555 CVE-2026-80557 CVE-2026-80558                      CVE-2026-80559 CVE-2026-80560 CVE-2026-80561 CVE-2026-80562                      CVE-2026-80565 CVE-2026-80567 CVE-2026-80568 CVE-2026-80569                      CVE-2026-80570 CVE-2026-80572 CVE-2026-80573 CVE-2026-80574                      CVE-2026-80583 CVE-2026-80584 CVE-2026-80586 CVE-2026-80589                      CVE-2026-80590 CVE-2026-80678 CVE-2026-80679 CVE-2026-80680                      CVE-2026-80681 CVE-2026-80684 CVE-2026-80686 CVE-2026-80706                      CVE-2026-80707 CVE-2026-80708 CVE-2026-80709 CVE-2026-80714                      CVE-2026-80715 CVE-2026-80716 CVE-2026-80717 CVE-2026-80718                      CVE-2026-80722 CVE-2026-80725 CVE-2026-80726 CVE-2026-80730                      CVE-2026-80731 CVE-2026-80732 CVE-2026-80733 CVE-2026-80737                      CVE-2026-80742 CVE-2026-80743 CVE-2026-80744 CVE-2026-80752                      CVE-2026-80754 CVE-2026-80756 CVE-2026-80757 CVE-2026-80762                      CVE-2026-80763 CVE-2026-80764 CVE-2026-80765 CVE-2026-80766                      CVE-2026-80767 CVE-2026-80768 CVE-2026-80770 CVE-2026-80772                      CVE-2026-80781 CVE-2026-80782 CVE-2026-80783 CVE-2026-80784                      CVE-2026-80788 CVE-2026-80789 CVE-2026-80790 CVE-2026-80791                      CVE-2026-80792 CVE-2026-80793 CVE-2026-80794 CVE-2026-80795                      CVE-2026-80796 CVE-2026-80797 CVE-2026-80798 CVE-2026-80799                      CVE-2026-80800 CVE-2026-80801 CVE-2026-80802 CVE-2026-80803                      CVE-2026-80805 CVE-2026-80806 CVE-2026-80807 CVE-2026-80808                      CVE-2026-80809 CVE-2026-80812 CVE-2026-80814 CVE-2026-80819                      CVE-2026-80823 CVE-2026-80824 CVE-2026-80826 CVE-2026-80827                      CVE-2026-80828 CVE-2026-80829 CVE-2026-80830 CVE-2026-80831                      CVE-2026-80832 CVE-2026-80840 CVE-2026-80842 CVE-2026-80843                      CVE-2026-80844 CVE-2026-80846 CVE-2026-80848 CVE-2026-80852                      CVE-2026-80854 CVE-2026-80855 CVE-2026-80856 CVE-2026-80863                      CVE-2026-80888 CVE-2026-80890 CVE-2026-80891 CVE-2026-80892                      CVE-2026-80893 CVE-2026-80901 CVE-2026-80902 CVE-2026-80904                      CVE-2026-80906 CVE-2026-80908 CVE-2026-80909 CVE-2026-80910                      CVE-2026-80913

    Several vulnerabilities have been discovered in the Linux kernel that     may lead to a privilege escalation, denial of service or information     leaks.

    For Debian 12 bookworm, these problems have been fixed in version     6.1.187-1.

    We recommend that you upgrade your linux packages.

    For the detailed security status of linux please refer to its security     tracker page at:
    https://security-tracker.debian.org/tracker/linux

    Further information about Debian LTS security advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://wiki.debian.org/LTS

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - net: bridge: mcast: fix use-after-free of a master VLAN's multicast context br_multicast_toggle_one_vlan()     clears BR_VLFLAG_MCAST_ENABLED under br->multicast_lock before stopping a VLAN's multicast context. That     is the teardown handshake: lockless readers gate on the flag through br_multicast_ctx_should_use() ->     br_multicast_ctx_vlan_disabled(), so once it is cleared under the lock no reader can arm the context     again. For a master VLAN the handshake never runs. __vlan_del() clears BRIDGE_VLAN_INFO_BRENTRY before     calling br_vlan_put_master(), so br_multicast_toggle_one_vlan(masterv, false) returns early on     !br_vlan_is_brentry(vlan): the flag stays set and br->multicast_lock is never taken. br_vlan_put_master()     then drains the context in br_multicast_ctx_deinit() and frees the VLAN through call_rcu(), while a reader     still inside rcu_read_lock() sees the context as enabled and re-arms it. The port and port-VLAN branch of     the function has no br_vlan_is_brentry() test and flips the flag under br->multicast_lock, so it is not     affected. The reader is the bridge transmit path. For a master VLAN br_multicast_rcv() selects brmctx =     &vlan->br_mcast_ctx with pmctx = NULL, so IGMP sent to the bridge device re-arms the context's timers     after br_multicast_ctx_deinit() has already stopped them. BUG: KASAN: slab-use-after-free in     detach_if_pending+0x412/0x4a0 Write of size 8 at addr ffff88810ac39918 by task brmc/601
    __mod_timer+0x51a/0xc50 br_multicast_host_join+0x25b/0x390 __br_multicast_add_group+0x468/0x530     br_ip4_multicast_add_group+0x1a0/0x260 br_multicast_rcv+0x2cda/0x61e0 br_dev_xmit+0x6c4/0x1540 Allocated     by task 610: br_vlan_add+0x111/0xb40 br_vlan_info+0x370/0x3e0 Freed by task 0: kfree+0x1a7/0x4f0     rcu_core+0x7dc/0x10a0 Only test br_vlan_is_brentry() when enabling, like the     br_multicast_ctx_vlan_global_disabled() test next to it. Disabling then always clears     BR_VLFLAG_MCAST_ENABLED under br->multicast_lock before br_multicast_ctx_deinit() drains the context.
    (CVE-2026-80842)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
351155	Debian dsa-6528 : ata-modules-6.12.111+deb13-armmp-di - security update	Nessus	Debian Local Security Checks	Local	high
351051	Amazon Linux 2 : kernel (ALASKERNEL-5.15-2026-116)	Nessus	Amazon Linux Local Security Checks	Local	high
343851	Debian dla-4777 : ata-modules-6.1.0-52-armmp-di - security update	Nessus	Debian Local Security Checks	Local	high
343039	Linux Distros Unpatched Vulnerability : CVE-2026-80842	Nessus	Misc.	Local	high

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