{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-31448", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.091Z", "datePublished": "2026-04-22T13:53:44.129Z", "dateUpdated": "2026-08-05T12:22:38.829Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:22:38.829Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: avoid infinite loops caused by residual data\n\nOn the mkdir/mknod path, when mapping logical blocks to physical blocks,\nif inserting a new extent into the extent tree fails (in this example,\nbecause the file system disabled the huge file feature when marking the\ninode as dirty), ext4_ext_map_blocks() only calls ext4_free_blocks() to\nreclaim the physical block without deleting the corresponding data in\nthe extent tree. This causes subsequent mkdir operations to reference\nthe previously reclaimed physical block number again, even though this\nphysical block is already being used by the xattr block. Therefore, a\nsituation arises where both the directory and xattr are using the same\nbuffer head block in memory simultaneously.\n\nThe above causes ext4_xattr_block_set() to enter an infinite loop about\n\"inserted\" and cannot release the inode lock, ultimately leading to the\n143s blocking problem mentioned in [1].\n\nIf the metadata is corrupted, then trying to remove some extent space\ncan do even more harm. Also in case EXT4_GET_BLOCKS_DELALLOC_RESERVE\nwas passed, remove space wrongly update quota information.\nJan Kara suggests distinguishing between two cases:\n\n1) The error is ENOSPC or EDQUOT - in this case the filesystem is fully\nconsistent and we must maintain its consistency including all the\naccounting. However these errors can happen only early before we've\ninserted the extent into the extent tree. So current code works correctly\nfor this case.\n\n2) Some other error - this means metadata is corrupted. We should strive to\ndo as few modifications as possible to limit damage. So I'd just skip\nfreeing of allocated blocks.\n\n[1]\nINFO: task syz.0.17:5995 blocked for more than 143 seconds.\nCall Trace:\n inode_lock_nested include/linux/fs.h:1073 [inline]\n __start_dirop fs/namei.c:2923 [inline]\n start_dirop fs/namei.c:2934 [inline]" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H", "baseScore": 9.4, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The vulnerable ext4 path is reachable through VFS mkdir/mknod/xattr operations, and the same operations can be driven remotely through in-kernel file servers such as ksmbd or nfsd on an ext4-backed writable export. A network-accessible writable share is a reasonable severe deployment scenario.\nAC:L - No race or probabilistic exploitation condition is required; once the affected ext4 state exists, the attacker can repeatedly drive the create/xattr sequence that reaches the stale extent mapping. The attacker controls the filesystem operations that trigger the hang.\nPR:N - In the most severe reasonable deployment, a guest/anonymous writable network export can expose the needed create operations without prior authentication. Locally, the same path only needs ordinary write permission on the directory, not kernel capabilities.\nUI:N - The attacker can trigger the vulnerable operations directly by issuing filesystem requests. No separate victim action is required in the network-export scenario.\nS:U - The impact remains within the Linux kernel/filesystem security authority. There is no VM escape, IOMMU bypass, or other cross-scope boundary crossing.\nC:L - The stale block aliasing can cause filesystem metadata/xattr contents to be interpreted through the wrong object, giving a plausible limited metadata disclosure risk. It is not a kernel memory arbitrary-read primitive.\nI:H - The bug creates a double-use physical block situation where directory and xattr metadata share the same buffer, allowing attacker-driven filesystem operations to corrupt security-relevant filesystem metadata. Given uncertainty about controllability of the aliased xattr block, the higher severity integrity value is selected.\nA:H - The observed failure is an infinite loop while holding inode locks, causing hung tasks for more than 143 seconds and repeatable filesystem denial of service. Kernel hung-task/deadlock conditions are high availability impact." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ext4/extents.c" ], "versions": [ { "version": "315054f023d28ee64f308adf8b5737831541776b", "lessThan": "c66545e83a802c3851d9be27a41c0479dd29ff0c", "status": "affected", "versionType": "git" }, { "version": "315054f023d28ee64f308adf8b5737831541776b", "lessThan": "ecc50bfca9b5c2ee6aeef998181689b80477367b", "status": "affected", "versionType": "git" }, { "version": "315054f023d28ee64f308adf8b5737831541776b", "lessThan": "3a7667595bcad84da53fc156a418e110267c3412", "status": "affected", "versionType": "git" }, { "version": "315054f023d28ee64f308adf8b5737831541776b", "lessThan": "416c86f30f91b4fb2642ef6b102596ca898f41a5", "status": "affected", "versionType": "git" }, { "version": "315054f023d28ee64f308adf8b5737831541776b", "lessThan": "64f425b06b3bea9abc8977fd3982779b3ad070c9", "status": "affected", "versionType": "git" }, { "version": "315054f023d28ee64f308adf8b5737831541776b", "lessThan": "5422fe71d26d42af6c454ca9527faaad4e677d6c", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ext4/extents.c" ], "versions": [ { "version": "2.6.22", "status": "affected" }, { "version": "0", "lessThan": "2.6.22", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.168", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.131", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.80", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.21", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.11", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.22", "versionEndExcluding": "6.1.168" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.22", "versionEndExcluding": "6.6.131" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.22", "versionEndExcluding": "6.12.80" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.22", "versionEndExcluding": "6.18.21" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.22", "versionEndExcluding": "6.19.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.22", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/c66545e83a802c3851d9be27a41c0479dd29ff0c" }, { "url": "https://git.kernel.org/stable/c/ecc50bfca9b5c2ee6aeef998181689b80477367b" }, { "url": "https://git.kernel.org/stable/c/3a7667595bcad84da53fc156a418e110267c3412" }, { "url": "https://git.kernel.org/stable/c/416c86f30f91b4fb2642ef6b102596ca898f41a5" }, { "url": "https://git.kernel.org/stable/c/64f425b06b3bea9abc8977fd3982779b3ad070c9" }, { "url": "https://git.kernel.org/stable/c/5422fe71d26d42af6c454ca9527faaad4e677d6c" } ], "title": "ext4: avoid infinite loops caused by residual data", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:47:54.473Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": 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