{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-63988 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-63988 is a medium-severity denial of service vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-63988 and fix it if it is affected.\n\nWhat it is: CVE-2026-63988 is a medium-severity denial of service vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-63988 in the wild and no public exploit code.\n\nAffected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-63988/ (Markdown: https://insights.sbomify.com/CVE-2026-63988/index.md)","id":"CVE-2026-63988","markdown":"https://insights.sbomify.com/CVE-2026-63988/index.md","name":"CVE-2026-63988","record":{"aliases":["BELL-CVE-2026-63988","DEBIAN-CVE-2026-63988","GHSA-qqj9-pc4p-85gc","UBUNTU-CVE-2026-63988"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel bridge","requires_auth":"low_privilege","summary":"A local attacker can trigger a kernel crash by writing to bridge port sysfs attributes, causing a sleep in atomic context.","user_interaction":"not_required","vuln_class":"denial_of_service"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":5.5,"severity":"medium","source":"nvd","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-667","name":"Improper Locking"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbridge: Fix sleep in atomic context in sysfs path\n\nSince the start of the git history, brport_store() always acquired the\nbridge lock. Back then this decision made sense: The bridge lock\nprotects the STP state of the bridge and its ports and at that time the\nfunction was only used by two STP related attributes (cost and\npriority).\n\nNowadays, brport_store() processes a lot more attributes and most of\nthem do not need the bridge lock:\n\n* Bridge flags: Only require RTNL. Read locklessly by the data path.\n  Annotations can be added in net-next.\n\n* FDB port flushing: Only requires the FDB lock.\n\n* Multicast attributes: Only require the multicast lock.\n\n* Group forward mask: Only requires RTNL. Read locklessly by the data\n  path. Annotations can be added in net-next.\n\n* Backup port: Only requires RTNL. Read locklessly by the data path.\n\nThis is a problem as the bridge calls dev_set_promiscuity() when certain\nbridge port flags change and this function can sleep since the commit\ncited below, resulting in a splat such as [1].\n\nFix this by reducing the scope of the bridge lock and only take it when\nprocessing the two STP related attributes that require it. Remove the\nnow stale comment from br_switchdev_set_port_flag(). The\nSWITCHDEV_F_DEFER flag can be removed in net-next.\n\n[1]\nBUG: sleeping function called from invalid context at net/core/dev_addr_lists.c:1262\nin_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 372, name: bash\npreempt_count: 201, expected: 0\nRCU nest depth: 0, expected: 0\n5 locks held by bash/372:\n#0: ffff88810c51c3f0 (sb_writers#7){.+.+}-{0:0}, at: ksys_write (fs/read_write.c:740)\n#1: ffff888115ce9480 (\u0026of-\u003emutex){+.+.}-{4:4}, at: kernfs_fop_write_iter (fs/kernfs/file.c:343)\n#2: ffff88810b9fd330 (kn-\u003eactive#37){.+.+}-{0:0}, at: kernfs_fop_write_iter (fs/kernfs/file.c:80 fs/kernfs/file.c:344)\n#3: ffffffffa59473a0 (rtnl_mutex){+.+.}-{4:4}, at: brport_store (net/bridge/br_sysfs_if.c:326)\n#4: ffff8881099d2d58 (\u0026br-\u003elock){+...}-{3:3}, at: brport_store (./include/linux/spinlock.h:348 net/bridge/br_sysfs_if.c:345)\nPreemption disabled at:\n 0x0\nHardware name: Bochs Bochs, BIOS Bochs 01/01/2011\nCall Trace:\n\u003cTASK\u003e\ndump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)\n__might_resched.cold (kernel/sched/core.c:9163)\nnetif_rx_mode_run (net/core/dev_addr_lists.c:1262)\nnetif_rx_mode_sync (net/core/dev_addr_lists.c:1428)\ndev_set_promiscuity (net/core/dev_api.c:289)\nbr_manage_promisc (net/bridge/br_if.c:135 net/bridge/br_if.c:172)\nbr_port_flags_change (net/bridge/br_if.c:242 net/bridge/br_if.c:747)\nstore_learning (net/bridge/br_sysfs_if.c:79 net/bridge/br_sysfs_if.c:235)\nbrport_store (net/bridge/br_sysfs_if.c:346)\nkernfs_fop_write_iter (fs/kernfs/file.c:352)\nnew_sync_write (fs/read_write.c:595)\nvfs_write (fs/read_write.c:688)\nksys_write (fs/read_write.c:740)\ndo_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)\nentry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"bridge: Fix sleep in atomic context in sysfs path","id":"CVE-2026-63988","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"denial_of_service","year":"2026"},"n_packages":0,"n_references":3,"next":{"headline":"bridge: Fix sleep in atomic context in netlink path","id":"CVE-2026-63989"},"packages":[],"prev":{"headline":"ethtool: coalesce: cap profile updates at NET_DIM_PARAMS_NUM_PROFILES","id":"CVE-2026-63987"},"products":["Linux"],"published":"2026-07-19","related":[{"cvss_score":8.8,"headline":"Linux Kernel Out-of-Bounds Write","id":"CVE-2026-53266","kev_date_added":"2026-09-18","published":"2026-06-25"},{"cvss_score":8.8,"headline":"Linux Kernel Improper Input Validation","id":"CVE-2013-6282","kev_date_added":"2022-09-15","published":"2013-11-19"},{"cvss_score":8.4,"headline":"Linux Kernel Heap-Based Buffer Overflow","id":"CVE-2022-0185","kev_date_added":"2024-08-21","published":"2022-02-11"},{"cvss_score":8.4,"headline":"Linux Kernel Privilege Escalation","id":"CVE-2013-2094","kev_date_added":"2022-09-15","published":"2013-05-14"},{"cvss_score":7.8,"headline":"Linux Kernel Unspecified","id":"CVE-2026-53362","kev_date_added":"2026-08-27","published":"2026-07-04"},{"cvss_score":7.8,"headline":"Linux Kernel Missing Initialization of a Variable","id":"CVE-2026-46300","kev_date_added":"2026-10-28","published":"2026-05-23"},{"cvss_score":7.8,"headline":"Linux Kernel Race Condition","id":"CVE-2025-39964","kev_date_added":"2026-09-18","published":"2025-10-13"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-07-19","vendors":["Linux"]},"summary":"A local attacker can trigger a kernel crash by writing to bridge port sysfs attributes, causing a sleep in atomic context.","url":"https://insights.sbomify.com/CVE-2026-63988/"}