{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2021-47544 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2021-47544 is a critical vulnerability in Linux kernel, published on 24 May 2024. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2021-47544 and fix it if it is affected.\n\nWhat it is: CVE-2021-47544 is a critical vulnerability in Linux kernel, published on 24 May 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2021-47544 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-2021-47544/ (Markdown: https://insights.sbomify.com/CVE-2021-47544/index.md)","id":"CVE-2021-47544","markdown":"https://insights.sbomify.com/CVE-2021-47544/index.md","name":"CVE-2021-47544","record":{"aliases":["DEBIAN-CVE-2021-47544","UBUNTU-CVE-2021-47544"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["data_modify"],"network_reachable":"yes","non_default_config":false,"product_category":"Linux kernel","requires_auth":"none","summary":"A race condition in the Linux kernel TCP stack can corrupt data streams when handling page faults during network transmission.","user_interaction":"not_required","vuln_class":"race_condition"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":9.8,"severity":"critical","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix page frag corruption on page fault\n\nSteffen reported a TCP stream corruption for HTTP requests\nserved by the apache web-server using a cifs mount-point\nand memory mapping the relevant file.\n\nThe root cause is quite similar to the one addressed by\ncommit 20eb4f29b602 (\"net: fix sk_page_frag() recursion from\nmemory reclaim\"). Here the nested access to the task page frag\nis caused by a page fault on the (mmapped) user-space memory\nbuffer coming from the cifs file.\n\nThe page fault handler performs an smb transaction on a different\nsocket, inside the same process context. Since sk-\u003esk_allaction\nfor such socket does not prevent the usage for the task_frag,\nthe nested allocation modify \"under the hood\" the page frag\nin use by the outer sendmsg call, corrupting the stream.\n\nThe overall relevant stack trace looks like the following:\n\nhttpd 78268 [001] 3461630.850950:      probe:tcp_sendmsg_locked:\n        ffffffff91461d91 tcp_sendmsg_locked+0x1\n        ffffffff91462b57 tcp_sendmsg+0x27\n        ffffffff9139814e sock_sendmsg+0x3e\n        ffffffffc06dfe1d smb_send_kvec+0x28\n        [...]\n        ffffffffc06cfaf8 cifs_readpages+0x213\n        ffffffff90e83c4b read_pages+0x6b\n        ffffffff90e83f31 __do_page_cache_readahead+0x1c1\n        ffffffff90e79e98 filemap_fault+0x788\n        ffffffff90eb0458 __do_fault+0x38\n        ffffffff90eb5280 do_fault+0x1a0\n        ffffffff90eb7c84 __handle_mm_fault+0x4d4\n        ffffffff90eb8093 handle_mm_fault+0xc3\n        ffffffff90c74f6d __do_page_fault+0x1ed\n        ffffffff90c75277 do_page_fault+0x37\n        ffffffff9160111e page_fault+0x1e\n        ffffffff9109e7b5 copyin+0x25\n        ffffffff9109eb40 _copy_from_iter_full+0xe0\n        ffffffff91462370 tcp_sendmsg_locked+0x5e0\n        ffffffff91462370 tcp_sendmsg_locked+0x5e0\n        ffffffff91462b57 tcp_sendmsg+0x27\n        ffffffff9139815c sock_sendmsg+0x4c\n        ffffffff913981f7 sock_write_iter+0x97\n        ffffffff90f2cc56 do_iter_readv_writev+0x156\n        ffffffff90f2dff0 do_iter_write+0x80\n        ffffffff90f2e1c3 vfs_writev+0xa3\n        ffffffff90f2e27c do_writev+0x5c\n        ffffffff90c042bb do_syscall_64+0x5b\n        ffffffff916000ad entry_SYSCALL_64_after_hwframe+0x65\n\nThe cifs filesystem rightfully sets sk_allocations to GFP_NOFS,\nwe can avoid the nesting using the sk page frag for allocation\nlacking the __GFP_FS flag. Do not define an additional mm-helper\nfor that, as this is strictly tied to the sk page frag usage.\n\nv1 -\u003e v2:\n - use a stricted sk_page_frag() check instead of reordering the\n   code (Eric)","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":"tcp: fix page frag corruption on page fault","id":"CVE-2021-47544","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"race_condition","year":"2021"},"n_packages":0,"n_references":3,"next":{"headline":"This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.","id":"CVE-2021-47545"},"packages":[],"prev":{"headline":"This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.","id":"CVE-2021-47543"},"products":["Linux"],"published":"2024-05-24","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":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-08-05","vendors":["Linux"]},"summary":"A race condition in the Linux kernel TCP stack can corrupt data streams when handling page faults during network transmission.","url":"https://insights.sbomify.com/CVE-2021-47544/"}