{"id":"CVE-2021-47107","revision":"907e6723528d46bfb1b771556bf6cee6","records":[{"revision":"907e6723528d46bfb1b771556bf6cee6","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2021-47107","aliases":[],"title":"NFSD: Fix READDIR buffer overflow","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Fix READDIR buffer overflow\n\nIf a client sends a READDIR count argument that is too small (say,\nzero), then the buffer size calculation in the new init_dirlist\nhelper functions results in an underflow, allowing the XDR stream\nfunctions to write beyond the actual buffer.\n\nThis calculation has always been suspect. NFSD has never sanity-\nchecked the READDIR count argument, but the old entry encoders\nmanaged the problem correctly.\n\nWith the commits below, entry encoding changed, exposing the\nunderflow to the pointer arithmetic in xdr_reserve_space().\n\nModern NFS clients attempt to retrieve as much data as possible\nfor each READDIR request. Also, we have no unit tests that\nexercise the behavior of READDIR at the lower bound of @count\nvalues. Thus this case was missed during testing.","state":0,"publishedAt":"2024-03-04T18:15:38.706+00:00","modifiedAt":"2026-10-14T12:12:18.48+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"fs/nfsd/nfs3proc.c\",\n                        \"fs/nfsd/nfsproc.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"37aa5e64022243e721b8334122997881177a4cfc\",\n                            \"lessThan\": \"9e291a6a28d32545ed2fd959a8165144d1724df1\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"7f87fc2d34d475225e78b7f5c4eabb121f4282b2\",\n                            \"lessThan\": \"eabc0aab98e5218ceecd82069b0d6fdfff5ee885\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"7f87fc2d34d475225e78b7f5c4eabb121f4282b2\",\n                            \"lessThan\": \"53b1119a6e5028b125f431a0116ba73510d82a72\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"fs/nfsd/nfs3proc.c\",\n                        \"fs/nfsd/nfsproc.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"5.13\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"5.13\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.15.12\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.16\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8,"severity":"CRITICAL"}],"references":["https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1","https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885","https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2021-47107","license":"CVE Program Terms of Use","key":"cve-program:CVE-2021-47107","identifiers":["CVE-2021-47107"]},"retained":false,"historicalAffected":[]}],"coverage":[]}