{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2021-47375 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2021-47375 is a medium-severity use after free vulnerability in Linux kernel, published on 21 May 2024. 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-2021-47375 and fix it if it is affected.\n\nWhat it is: CVE-2021-47375 is a medium-severity use after free vulnerability in Linux kernel, published on 21 May 2024. 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-2021-47375 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-2021-47375/ (Markdown: https://insights.sbomify.com/CVE-2021-47375/index.md)","id":"CVE-2021-47375","markdown":"https://insights.sbomify.com/CVE-2021-47375/index.md","name":"CVE-2021-47375","record":{"aliases":["DEBIAN-CVE-2021-47375","GHSA-x6vg-gvf6-hmp9","UBUNTU-CVE-2021-47375"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel","requires_auth":"none","summary":"A use-after-free vulnerability in the Linux kernel's blktrace subsystem allows local attackers to cause a system crash via race conditions during trace removal.","user_interaction":"not_required","vuln_class":"use_after_free"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":6.2,"severity":"medium","source":"cisa-adp","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","version":"3.1"},"cwes":[{"id":"CWE-416","name":"Use After Free"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nblktrace: Fix uaf in blk_trace access after removing by sysfs\n\nThere is an use-after-free problem triggered by following process:\n\n      P1(sda)\t\t\t\tP2(sdb)\n\t\t\techo 0 \u003e /sys/block/sdb/trace/enable\n\t\t\t  blk_trace_remove_queue\n\t\t\t    synchronize_rcu\n\t\t\t    blk_trace_free\n\t\t\t      relay_close\nrcu_read_lock\n__blk_add_trace\n  trace_note_tsk\n  (Iterate running_trace_list)\n\t\t\t        relay_close_buf\n\t\t\t\t  relay_destroy_buf\n\t\t\t\t    kfree(buf)\n    trace_note(sdb's bt)\n      relay_reserve\n        buf-\u003eoffset \u003c- nullptr deference (use-after-free) !!!\nrcu_read_unlock\n\n[  502.714379] BUG: kernel NULL pointer dereference, address:\n0000000000000010\n[  502.715260] #PF: supervisor read access in kernel mode\n[  502.715903] #PF: error_code(0x0000) - not-present page\n[  502.716546] PGD 103984067 P4D 103984067 PUD 17592b067 PMD 0\n[  502.717252] Oops: 0000 [#1] SMP\n[  502.720308] RIP: 0010:trace_note.isra.0+0x86/0x360\n[  502.732872] Call Trace:\n[  502.733193]  __blk_add_trace.cold+0x137/0x1a3\n[  502.733734]  blk_add_trace_rq+0x7b/0xd0\n[  502.734207]  blk_add_trace_rq_issue+0x54/0xa0\n[  502.734755]  blk_mq_start_request+0xde/0x1b0\n[  502.735287]  scsi_queue_rq+0x528/0x1140\n...\n[  502.742704]  sg_new_write.isra.0+0x16e/0x3e0\n[  502.747501]  sg_ioctl+0x466/0x1100\n\nReproduce method:\n  ioctl(/dev/sda, BLKTRACESETUP, blk_user_trace_setup[buf_size=127])\n  ioctl(/dev/sda, BLKTRACESTART)\n  ioctl(/dev/sdb, BLKTRACESETUP, blk_user_trace_setup[buf_size=127])\n  ioctl(/dev/sdb, BLKTRACESTART)\n\n  echo 0 \u003e /sys/block/sdb/trace/enable \u0026\n  // Add delay(mdelay/msleep) before kernel enters blk_trace_free()\n\n  ioctl$SG_IO(/dev/sda, SG_IO, ...)\n  // Enters trace_note_tsk() after blk_trace_free() returned\n  // Use mdelay in rcu region rather than msleep(which may schedule out)\n\nRemove blk_trace from running_list before calling blk_trace_free() by\nsysfs if blk_trace is at Blktrace_running state.","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":"blktrace: Fix uaf in blk_trace access after removing by sysfs","id":"CVE-2021-47375","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"use_after_free","year":"2021"},"n_packages":0,"n_references":8,"next":{"headline":"bpf: Add oversize check before call kvcalloc()","id":"CVE-2021-47376"},"packages":[],"prev":{"headline":"dma-debug: prevent an error message from causing runtime problems","id":"CVE-2021-47374"},"products":["Linux"],"published":"2024-05-21","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":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-05-11","vendors":["Linux"]},"summary":"A use-after-free vulnerability in the Linux kernel's blktrace subsystem allows local attackers to cause a system crash via race conditions during trace removal.","url":"https://insights.sbomify.com/CVE-2021-47375/"}