{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63954", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.023Z", "datePublished": "2026-07-19T14:55:46.183Z", "dateUpdated": "2026-08-05T12:37:38.482Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:37:38.482Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nhpfs: fix a crash if hpfs_map_dnode_bitmap fails\n\nIf hpfs_map_dnode_bitmap fails, the code would call hpfs_brelse4 on\nuninitialized quad buffer head, causing a crash." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is reached only through local VFS syscalls (mkdir, create, unlink, rename) on a mounted HPFS filesystem; HPFS is a local block-device filesystem with no network-facing kernel server component.\nAC:L - An attacker can reliably force `hpfs_map_dnode_bitmap()` to fail by mounting a crafted image (e.g. with `check=none` and an invalid `dir_band_bitmap`) or by corrupting the loop/backing device after mount to induce read errors, then triggering a directory operation.\nPR:L - Exploitation requires mounting HPFS (achievable with CAP_SYS_ADMIN inside an unprivileged user namespace) and write access to the mountpoint; it does not require real root in the initial namespace.\nUI:N - In the highest-impact path, the attacker mounts their own malicious HPFS image inside a user namespace and triggers the bug themselves without requiring any victim action such as plugging in media or mounting untrusted storage.\nS:U - Impact is confined to kernel memory management within the same kernel security domain; there is no crossing of VM, container, or IOMMU boundaries.\nC:H - Calling `hpfs_brelse4()` on an uninitialized `quad_buffer_head` performs `kfree()` and `brelse()` on stack garbage, which is uncontrolled memory corruption that can corrupt slab metadata or dereference arbitrary pointers, not a bounded NULL dereference.\nI:H - The erroneous `kfree()`/`brelse()` calls on uninitialized pointers can corrupt kernel heap state and potentially be leveraged for arbitrary writes, matching the guidance to score uncertain memory-corruption bugs at High.\nA:H - The bug reliably causes a kernel oops or panic when `hpfs_map_dnode_bitmap()` fails, resulting in complete loss of system availability for the affected host." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/hpfs/alloc.c" ], "versions": [ { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "010b08084000ef018f1a8de5197087f3b91d8cfe", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "d98d8562b3284b5a5c8eb67e71b794508e46e288", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "1648a3c7f4e18f46a4881920133fc4f2494185a0", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "7c58c55a2a16f7274772507bd1637be609351b4f", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "1d73a533760bc5abb83b3cc759133596f7bb708f", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "0886c6f257fe3663f80218aa1919b0f3f21bf22c", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "4f37bb30b57d6d403d02673074555bd3c3602bef", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "974820a59efde7c1a7e1260bcfe9bb81f833cc9f", "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/hpfs/alloc.c" ], "versions": [ { "version": "2.6.12", "status": "affected" }, { "version": "0", "lessThan": "2.6.12", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.259", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.210", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.176", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.93", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.35", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.12", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "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": "2.6.12", "versionEndExcluding": "5.10.259" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.15.210" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.1.176" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.6.143" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.12.93" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.18.35" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.0.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/010b08084000ef018f1a8de5197087f3b91d8cfe" }, { "url": "https://git.kernel.org/stable/c/d98d8562b3284b5a5c8eb67e71b794508e46e288" }, { "url": "https://git.kernel.org/stable/c/1648a3c7f4e18f46a4881920133fc4f2494185a0" }, { "url": "https://git.kernel.org/stable/c/7c58c55a2a16f7274772507bd1637be609351b4f" }, { "url": "https://git.kernel.org/stable/c/1d73a533760bc5abb83b3cc759133596f7bb708f" }, { "url": "https://git.kernel.org/stable/c/0886c6f257fe3663f80218aa1919b0f3f21bf22c" }, { "url": "https://git.kernel.org/stable/c/4f37bb30b57d6d403d02673074555bd3c3602bef" }, { "url": "https://git.kernel.org/stable/c/974820a59efde7c1a7e1260bcfe9bb81f833cc9f" } ], "title": "hpfs: fix a crash if hpfs_map_dnode_bitmap fails", "x_generator": { "engine": "bippy-1.2.0" } } } }