{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-46052", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-13T15:03:33.094Z", "datePublished": "2026-05-27T12:57:10.777Z", "dateUpdated": "2026-08-05T12:29:20.131Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:29:20.131Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: only d_add() negative dentries when they are unhashed\n\nCeph can call d_add(dentry, NULL) on a negative dentry that is already\npresent in the primary dcache hash.\n\nIn the current VFS that is not safe. d_add() goes through __d_add()\nto __d_rehash(), which unconditionally reinserts dentry->d_hash into\nthe hlist_bl bucket. If the dentry is already hashed, reinserting the\nsame node can corrupt the bucket, including creating a self-loop.\nOnce that happens, __d_lookup() can spin forever in the hlist_bl walk,\ntypically looping only on the d_name.hash mismatch check and\neventually triggering RCU stall reports like this one:\n\n rcu: INFO: rcu_sched self-detected stall on CPU\n rcu: 87-....: (2100 ticks this GP) idle=3a4c/1/0x4000000000000000 softirq=25003319/25003319 fqs=829\n rcu: (t=2101 jiffies g=79058445 q=698988 ncpus=192)\n CPU: 87 UID: 2952868916 PID: 3933303 Comm: php-cgi8.3 Not tainted 6.18.17-i1-amd #950 NONE\n Hardware name: Dell Inc. PowerEdge R7615/0G9DHV, BIOS 1.6.6 09/22/2023\n RIP: 0010:__d_lookup+0x46/0xb0\n Code: c1 e8 07 48 8d 04 c2 48 8b 00 49 89 fc 49 89 f5 48 89 c3 48 83 e3 fe 48 83 f8 01 77 0f eb 2d 0f 1f 44 00 00 48 8b 1b 48 85 db <74> 20 39 6b 18 75 f3 48 8d 7b 78 e8 ba 85 d0 00 4c 39 63 10 74 1f\n RSP: 0018:ff745a70c8253898 EFLAGS: 00000282\n RAX: ff26e470054cb208 RBX: ff26e470054cb208 RCX: 000000006e958966\n RDX: ff26e48267340000 RSI: ff745a70c82539b0 RDI: ff26e458f74655c0\n RBP: 000000006e958966 R08: 0000000000000180 R09: 9cd08d909b919a89\n R10: ff26e458f74655c0 R11: 0000000000000000 R12: ff26e458f74655c0\n R13: ff745a70c82539b0 R14: d0d0d0d0d0d0d0d0 R15: 2f2f2f2f2f2f2f2f\n FS: 00007f5770896980(0000) GS:ff26e482c5d88000(0000) knlGS:0000000000000000\n CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 00007f5764de50c0 CR3: 000000a72abb5001 CR4: 0000000000771ef0\n PKRU: 55555554\n Call Trace:\n \n lookup_fast+0x9f/0x100\n walk_component+0x1f/0x150\n link_path_walk+0x20e/0x3d0\n path_lookupat+0x68/0x180\n filename_lookup+0xdc/0x1e0\n vfs_statx+0x6c/0x140\n vfs_fstatat+0x67/0xa0\n __do_sys_newfstatat+0x24/0x60\n do_syscall_64+0x6a/0x230\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nThis is reachable with reused cached negative dentries. A Ceph lookup\nor atomic_open can be handed a negative dentry that is already hashed,\nand fs/ceph/dir.c then hits one of two paths that incorrectly assume\n\"negative\" also means \"unhashed\":\n\n - ceph_finish_lookup():\n MDS reply is -ENOENT with no trace\n -> d_add(dentry, NULL)\n\n - ceph_lookup():\n local ENOENT fast path for a complete directory with shared caps\n -> d_add(dentry, NULL)\n\nBoth paths can therefore re-add an already-hashed negative dentry.\n\nCeph already uses the correct pattern elsewhere: ceph_fill_trace() only\ncalls d_add(dn, NULL) for a negative null-dentry reply when d_unhashed(dn)\nis true.\n\nFix both fs/ceph/dir.c sites the same way: only call d_add() for a\nnegative dentry when it is actually unhashed. If the negative dentry\nis already hashed, leave it in place and reuse it as-is.\n\nThis preserves the existing behavior for unhashed dentries while\navoiding d_hash list corruption for reused hashed negatives." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - Ceph is a network filesystem client; the vulnerable `ceph_finish_lookup()` path is driven directly by remote MDS reply data (-ENOENT with no trace), so a malicious/compromised MDS or on-path attacker injecting crafted replies can drive the buggy `d_add()` on a hashed negative dentry. Processing remote-peer data places this at Network.\nAC:L - The corruption arose naturally in production from an ordinary `newfstatat`, showing the precondition (a reused already-hashed negative dentry) is reliably reachable; an attacker controlling MDS replies/lease grants can deterministically set up the cached negative dentry and re-lookup with no race outside their control.\nPR:N - A network attacker who controls or impersonates the MDS (or MITMs the unauthenticated msgr path) needs no privileges or credentials on the victim client to feed the -ENOENT-no-trace replies that trigger the vulnerable code.\nUI:N - On an established Ceph mount, path lookups/stats occur continuously as part of normal operation, so no specific victim action is required at exploit time.\nS:U - The corruption and resulting hang are entirely within the kernel's own dcache; no security boundary (VM, IOMMU, sandbox) is crossed.\nC:N - The bug creates a self-referential cycle in an hlist_bl hash bucket and leaks no memory contents; there is no out-of-bounds or use-after-free read primitive.\nI:N - The only state altered is an internal dcache list pointer forming a loop; this provides no attacker-controllable write primitive and modifies no user or security-relevant data.\nA:H - `__d_lookup()` spins forever on the corrupted bucket, producing RCU stalls and a hung/softlocked CPU — a kernel-level denial of service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ceph/dir.c" ], "versions": [ { "version": "2817b000b02c5f0c05af67c01fb2684e1381d6ef", "lessThan": "4147ae08824cc8b65d2b2018f79d416af2937108", "status": "affected", "versionType": "git" }, { "version": "2817b000b02c5f0c05af67c01fb2684e1381d6ef", "lessThan": "73b47a1f06dee5e61b00dee5227d75d3f1f6d977", "status": "affected", "versionType": "git" }, { "version": "2817b000b02c5f0c05af67c01fb2684e1381d6ef", "lessThan": "79ffcbeac6bc1dc1bcdb0434acf250f6215ec111", "status": "affected", "versionType": "git" }, { "version": "2817b000b02c5f0c05af67c01fb2684e1381d6ef", "lessThan": "83ce43a21bb7df8dd52228afdd918d2d058eefde", "status": "affected", "versionType": "git" }, { "version": "2817b000b02c5f0c05af67c01fb2684e1381d6ef", "lessThan": "4179cc390dacebc87079419ec92f86f3dc46294d", "status": "affected", "versionType": "git" }, { "version": "2817b000b02c5f0c05af67c01fb2684e1381d6ef", "lessThan": "b91e535f208c48a5e7464f1aa38338a30e7912df", "status": "affected", "versionType": "git" }, { "version": "2817b000b02c5f0c05af67c01fb2684e1381d6ef", "lessThan": "2010cb06b9df7d3c816c78358c566bdacbdf38ff", "status": "affected", "versionType": "git" }, { "version": "2817b000b02c5f0c05af67c01fb2684e1381d6ef", "lessThan": "803447f93d75ab6e40c85e6d12b5630d281d70d6", "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/ceph/dir.c" ], "versions": [ { "version": "2.6.34", "status": "affected" }, { "version": "0", "lessThan": "2.6.34", "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": "6.6.140", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.86", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.27", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.4", "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": "2.6.34", "versionEndExcluding": "5.10.259" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "5.15.210" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.1.176" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.6.140" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.12.86" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.18.27" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "7.0.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/4147ae08824cc8b65d2b2018f79d416af2937108" }, { "url": "https://git.kernel.org/stable/c/73b47a1f06dee5e61b00dee5227d75d3f1f6d977" }, { "url": "https://git.kernel.org/stable/c/79ffcbeac6bc1dc1bcdb0434acf250f6215ec111" }, { "url": "https://git.kernel.org/stable/c/83ce43a21bb7df8dd52228afdd918d2d058eefde" }, { "url": "https://git.kernel.org/stable/c/4179cc390dacebc87079419ec92f86f3dc46294d" }, { "url": "https://git.kernel.org/stable/c/b91e535f208c48a5e7464f1aa38338a30e7912df" }, { "url": "https://git.kernel.org/stable/c/2010cb06b9df7d3c816c78358c566bdacbdf38ff" }, { "url": "https://git.kernel.org/stable/c/803447f93d75ab6e40c85e6d12b5630d281d70d6" } ], "title": "ceph: only d_add() negative dentries when they are unhashed", "x_generator": { "engine": "bippy-1.2.0" } } } }