{"id":"CVE-2021-4090","title":"An out-of-bounds (OOB) memory write flaw was found in the NFSD in the Linux kernel","summary":"An out-of-bounds (OOB) memory write flaw was found in the NFSD in the Linux kernel. Missing sanity may lead to a write beyond bmval[bmlen-1] in nfsd4_decode_bitmap4 in fs/nfsd/nfs4xdr.c. In this flaw, a local attacker with user privilege…","severity":"high","cvss":7.1,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","cwe":["CWE-787","CWE-787"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel < 5.16","linux_kernel = 5.16","h300s_firmware","h500s_firmware","h700s_firmware","h300e_firmware","h500e_firmware","h700e_firmware","h410s_firmware","h410c_firmware"],"patched":["linux_kernel 5.16"],"published":"2022-02-18","updated":"2026-08-25","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-4090","references":[{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2025101","label":"secalert@redhat.com"},{"url":"https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c0019b7db1d7ac62c711cda6b357a659d46428fe","label":"secalert@redhat.com"},{"url":"https://lore.kernel.org/linux-nfs/163692036074.16710.5678362976688977923.stgit%40klimt.1015granger.net/","label":"secalert@redhat.com"},{"url":"https://security.netapp.com/advisory/ntap-20220318-0010/","label":"secalert@redhat.com"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2025101","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lore.kernel.org/linux-nfs/163692036074.16710.5678362976688977923.stgit%40klimt.1015granger.net/","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.netapp.com/advisory/ntap-20220318-0010/","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-265688.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd"],"epss":0.00339,"epssPercentile":0.27353,"ingestedAt":"2026-08-25T19:31:02.469Z","slug":"CVE-2021-4090","body":"## Overview\n\nAn out-of-bounds (OOB) memory write flaw was found in the NFSD in the Linux kernel. Missing sanity may lead to a write beyond bmval[bmlen-1] in nfsd4_decode_bitmap4 in fs/nfsd/nfs4xdr.c. In this flaw, a local attacker with user privilege may gain access to out-of-bounds memory, leading to a system integrity and confidentiality threat.\n\n## Affected\n\n- `linux_kernel < 5.16`\n- `linux_kernel = 5.16`\n- `h300s_firmware`\n- `h500s_firmware`\n- `h700s_firmware`\n- `h300e_firmware`\n- `h500e_firmware`\n- `h700e_firmware`\n- `h410s_firmware`\n- `h410c_firmware`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 5.16`","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":39.1,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}