CVE-2026-43420 (GCVE-0-2026-43420)

Vulnerability from cvelistv5 – Published: 2026-05-08 14:21 – Updated: 2026-05-11 22:24
VLAI
Title
ceph: fix i_nlink underrun during async unlink
Summary
In the Linux kernel, the following vulnerability has been resolved: ceph: fix i_nlink underrun during async unlink During async unlink, we drop the `i_nlink` counter before we receive the completion (that will eventually update the `i_nlink`) because "we assume that the unlink will succeed". That is not a bad idea, but it races against deletions by other clients (or against the completion of our own unlink) and can lead to an underrun which emits a WARNING like this one: WARNING: CPU: 85 PID: 25093 at fs/inode.c:407 drop_nlink+0x50/0x68 Modules linked in: CPU: 85 UID: 3221252029 PID: 25093 Comm: php-cgi8.1 Not tainted 6.14.11-cm4all1-ampere #655 Hardware name: Supermicro ARS-110M-NR/R12SPD-A, BIOS 1.1b 10/17/2023 pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : drop_nlink+0x50/0x68 lr : ceph_unlink+0x6c4/0x720 sp : ffff80012173bc90 x29: ffff80012173bc90 x28: ffff086d0a45aaf8 x27: ffff0871d0eb5680 x26: ffff087f2a64a718 x25: 0000020000000180 x24: 0000000061c88647 x23: 0000000000000002 x22: ffff07ff9236d800 x21: 0000000000001203 x20: ffff07ff9237b000 x19: ffff088b8296afc0 x18: 00000000f3c93365 x17: 0000000000070000 x16: ffff08faffcbdfe8 x15: ffff08faffcbdfec x14: 0000000000000000 x13: 45445f65645f3037 x12: 34385f6369706f74 x11: 0000a2653104bb20 x10: ffffd85f26d73290 x9 : ffffd85f25664f94 x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000002 x5 : 0000000000000081 x4 : 0000000000000481 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff08727d3f91e8 Call trace: drop_nlink+0x50/0x68 (P) vfs_unlink+0xb0/0x2e8 do_unlinkat+0x204/0x288 __arm64_sys_unlinkat+0x3c/0x80 invoke_syscall.constprop.0+0x54/0xe8 do_el0_svc+0xa4/0xc8 el0_svc+0x18/0x58 el0t_64_sync_handler+0x104/0x130 el0t_64_sync+0x154/0x158 In ceph_unlink(), a call to ceph_mdsc_submit_request() submits the CEPH_MDS_OP_UNLINK to the MDS, but does not wait for completion. Meanwhile, between this call and the following drop_nlink() call, a worker thread may process a CEPH_CAP_OP_IMPORT, CEPH_CAP_OP_GRANT or just a CEPH_MSG_CLIENT_REPLY (the latter of which could be our own completion). These will lead to a set_nlink() call, updating the `i_nlink` counter to the value received from the MDS. If that new `i_nlink` value happens to be zero, it is illegal to decrement it further. But that is exactly what ceph_unlink() will do then. The WARNING can be reproduced this way: 1. Force async unlink; only the async code path is affected. Having no real clue about Ceph internals, I was unable to find out why the MDS wouldn't give me the "Fxr" capabilities, so I patched get_caps_for_async_unlink() to always succeed. (Note that the WARNING dump above was found on an unpatched kernel, without this kludge - this is not a theoretical bug.) 2. Add a sleep call after ceph_mdsc_submit_request() so the unlink completion gets handled by a worker thread before drop_nlink() is called. This guarantees that the `i_nlink` is already zero before drop_nlink() runs. The solution is to skip the counter decrement when it is already zero, but doing so without a lock is still racy (TOCTOU). Since ceph_fill_inode() and handle_cap_grant() both hold the `ceph_inode_info.i_ceph_lock` spinlock while set_nlink() runs, this seems like the proper lock to protect the `i_nlink` updates. I found prior art in NFS and SMB (using `inode.i_lock`) and AFS (using `afs_vnode.cb_lock`). All three have the zero check as well.
Severity
4.7 (Medium)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 2ccb45462aeaf0831397b90d31d3d50a7704fa1f , < 9b31e88ac5623d15c8bc46f69dfe1d3b43a8f67c (git)
Affected: 2ccb45462aeaf0831397b90d31d3d50a7704fa1f , < 6d5fd8bb574bef039eb3b738e523870433a2aeb9 (git)
Affected: 2ccb45462aeaf0831397b90d31d3d50a7704fa1f , < fcc477a6e8856c8a42b3c9e171724d8d6dfadd06 (git)
Affected: 2ccb45462aeaf0831397b90d31d3d50a7704fa1f , < b3f5513141ecc6b277a8f7b7efe58a0cf9a5e859 (git)
Affected: 2ccb45462aeaf0831397b90d31d3d50a7704fa1f , < aedd29386b23f3e1e6818943e11abfff2953732f (git)
Affected: 2ccb45462aeaf0831397b90d31d3d50a7704fa1f , < 7db008e85a5d17b64bc5390b828bf457ae91a415 (git)
Affected: 2ccb45462aeaf0831397b90d31d3d50a7704fa1f , < 8975b85b0d45ca811ace6fac5907652f2310e5ac (git)
Affected: 2ccb45462aeaf0831397b90d31d3d50a7704fa1f , < ce0123cbb4a40a2f1bbb815f292b26e96088639f (git)
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Linux Linux Affected: 5.7
Unaffected: 0 , < 5.7 (semver)
Unaffected: 5.10.253 , ≤ 5.10.* (semver)
Unaffected: 5.15.203 , ≤ 5.15.* (semver)
Unaffected: 6.1.167 , ≤ 6.1.* (semver)
Unaffected: 6.6.130 , ≤ 6.6.* (semver)
Unaffected: 6.12.78 , ≤ 6.12.* (semver)
Unaffected: 6.18.19 , ≤ 6.18.* (semver)
Unaffected: 6.19.9 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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{
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix i_nlink underrun during async unlink\n\nDuring async unlink, we drop the `i_nlink` counter before we receive\nthe completion (that will eventually update the `i_nlink`) because \"we\nassume that the unlink will succeed\".  That is not a bad idea, but it\nraces against deletions by other clients (or against the completion of\nour own unlink) and can lead to an underrun which emits a WARNING like\nthis one:\n\n WARNING: CPU: 85 PID: 25093 at fs/inode.c:407 drop_nlink+0x50/0x68\n Modules linked in:\n CPU: 85 UID: 3221252029 PID: 25093 Comm: php-cgi8.1 Not tainted 6.14.11-cm4all1-ampere #655\n Hardware name: Supermicro ARS-110M-NR/R12SPD-A, BIOS 1.1b 10/17/2023\n pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)\n pc : drop_nlink+0x50/0x68\n lr : ceph_unlink+0x6c4/0x720\n sp : ffff80012173bc90\n x29: ffff80012173bc90 x28: ffff086d0a45aaf8 x27: ffff0871d0eb5680\n x26: ffff087f2a64a718 x25: 0000020000000180 x24: 0000000061c88647\n x23: 0000000000000002 x22: ffff07ff9236d800 x21: 0000000000001203\n x20: ffff07ff9237b000 x19: ffff088b8296afc0 x18: 00000000f3c93365\n x17: 0000000000070000 x16: ffff08faffcbdfe8 x15: ffff08faffcbdfec\n x14: 0000000000000000 x13: 45445f65645f3037 x12: 34385f6369706f74\n x11: 0000a2653104bb20 x10: ffffd85f26d73290 x9 : ffffd85f25664f94\n x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000002\n x5 : 0000000000000081 x4 : 0000000000000481 x3 : 0000000000000000\n x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff08727d3f91e8\n Call trace:\n  drop_nlink+0x50/0x68 (P)\n  vfs_unlink+0xb0/0x2e8\n  do_unlinkat+0x204/0x288\n  __arm64_sys_unlinkat+0x3c/0x80\n  invoke_syscall.constprop.0+0x54/0xe8\n  do_el0_svc+0xa4/0xc8\n  el0_svc+0x18/0x58\n  el0t_64_sync_handler+0x104/0x130\n  el0t_64_sync+0x154/0x158\n\nIn ceph_unlink(), a call to ceph_mdsc_submit_request() submits the\nCEPH_MDS_OP_UNLINK to the MDS, but does not wait for completion.\n\nMeanwhile, between this call and the following drop_nlink() call, a\nworker thread may process a CEPH_CAP_OP_IMPORT, CEPH_CAP_OP_GRANT or\njust a CEPH_MSG_CLIENT_REPLY (the latter of which could be our own\ncompletion).  These will lead to a set_nlink() call, updating the\n`i_nlink` counter to the value received from the MDS.  If that new\n`i_nlink` value happens to be zero, it is illegal to decrement it\nfurther.  But that is exactly what ceph_unlink() will do then.\n\nThe WARNING can be reproduced this way:\n\n1. Force async unlink; only the async code path is affected.  Having\n   no real clue about Ceph internals, I was unable to find out why the\n   MDS wouldn\u0027t give me the \"Fxr\" capabilities, so I patched\n   get_caps_for_async_unlink() to always succeed.\n\n   (Note that the WARNING dump above was found on an unpatched kernel,\n   without this kludge - this is not a theoretical bug.)\n\n2. Add a sleep call after ceph_mdsc_submit_request() so the unlink\n   completion gets handled by a worker thread before drop_nlink() is\n   called.  This guarantees that the `i_nlink` is already zero before\n   drop_nlink() runs.\n\nThe solution is to skip the counter decrement when it is already zero,\nbut doing so without a lock is still racy (TOCTOU).  Since\nceph_fill_inode() and handle_cap_grant() both hold the\n`ceph_inode_info.i_ceph_lock` spinlock while set_nlink() runs, this\nseems like the proper lock to protect the `i_nlink` updates.\n\nI found prior art in NFS and SMB (using `inode.i_lock`) and AFS (using\n`afs_vnode.cb_lock`).  All three have the zero check as well."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T22:24:14.623Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/9b31e88ac5623d15c8bc46f69dfe1d3b43a8f67c"
        },
        {
          "url": "https://git.kernel.org/stable/c/6d5fd8bb574bef039eb3b738e523870433a2aeb9"
        },
        {
          "url": "https://git.kernel.org/stable/c/fcc477a6e8856c8a42b3c9e171724d8d6dfadd06"
        },
        {
          "url": "https://git.kernel.org/stable/c/b3f5513141ecc6b277a8f7b7efe58a0cf9a5e859"
        },
        {
          "url": "https://git.kernel.org/stable/c/aedd29386b23f3e1e6818943e11abfff2953732f"
        },
        {
          "url": "https://git.kernel.org/stable/c/7db008e85a5d17b64bc5390b828bf457ae91a415"
        },
        {
          "url": "https://git.kernel.org/stable/c/8975b85b0d45ca811ace6fac5907652f2310e5ac"
        },
        {
          "url": "https://git.kernel.org/stable/c/ce0123cbb4a40a2f1bbb815f292b26e96088639f"
        }
      ],
      "title": "ceph: fix i_nlink underrun during async unlink",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43420",
    "datePublished": "2026-05-08T14:21:55.717Z",
    "dateReserved": "2026-05-01T14:12:56.008Z",
    "dateUpdated": "2026-05-11T22:24:14.623Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-43420",
      "date": "2026-08-26",
      "epss": "0.00093",
      "percentile": "0.00636"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-43420\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-05-08T15:16:54.023\",\"lastModified\":\"2026-06-17T10:49:33.837\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nceph: fix i_nlink underrun during async unlink\\n\\nDuring async unlink, we drop the `i_nlink` counter before we receive\\nthe completion (that will eventually update the `i_nlink`) because \\\"we\\nassume that the unlink will succeed\\\".  That is not a bad idea, but it\\nraces against deletions by other clients (or against the completion of\\nour own unlink) and can lead to an underrun which emits a WARNING like\\nthis one:\\n\\n WARNING: CPU: 85 PID: 25093 at fs/inode.c:407 drop_nlink+0x50/0x68\\n Modules linked in:\\n CPU: 85 UID: 3221252029 PID: 25093 Comm: php-cgi8.1 Not tainted 6.14.11-cm4all1-ampere #655\\n Hardware name: Supermicro ARS-110M-NR/R12SPD-A, BIOS 1.1b 10/17/2023\\n pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)\\n pc : drop_nlink+0x50/0x68\\n lr : ceph_unlink+0x6c4/0x720\\n sp : ffff80012173bc90\\n x29: ffff80012173bc90 x28: ffff086d0a45aaf8 x27: ffff0871d0eb5680\\n x26: ffff087f2a64a718 x25: 0000020000000180 x24: 0000000061c88647\\n x23: 0000000000000002 x22: ffff07ff9236d800 x21: 0000000000001203\\n x20: ffff07ff9237b000 x19: ffff088b8296afc0 x18: 00000000f3c93365\\n x17: 0000000000070000 x16: ffff08faffcbdfe8 x15: ffff08faffcbdfec\\n x14: 0000000000000000 x13: 45445f65645f3037 x12: 34385f6369706f74\\n x11: 0000a2653104bb20 x10: ffffd85f26d73290 x9 : ffffd85f25664f94\\n x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000002\\n x5 : 0000000000000081 x4 : 0000000000000481 x3 : 0000000000000000\\n x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff08727d3f91e8\\n Call trace:\\n  drop_nlink+0x50/0x68 (P)\\n  vfs_unlink+0xb0/0x2e8\\n  do_unlinkat+0x204/0x288\\n  __arm64_sys_unlinkat+0x3c/0x80\\n  invoke_syscall.constprop.0+0x54/0xe8\\n  do_el0_svc+0xa4/0xc8\\n  el0_svc+0x18/0x58\\n  el0t_64_sync_handler+0x104/0x130\\n  el0t_64_sync+0x154/0x158\\n\\nIn ceph_unlink(), a call to ceph_mdsc_submit_request() submits the\\nCEPH_MDS_OP_UNLINK to the MDS, but does not wait for completion.\\n\\nMeanwhile, between this call and the following drop_nlink() call, a\\nworker thread may process a CEPH_CAP_OP_IMPORT, CEPH_CAP_OP_GRANT or\\njust a CEPH_MSG_CLIENT_REPLY (the latter of which could be our own\\ncompletion).  These will lead to a set_nlink() call, updating the\\n`i_nlink` counter to the value received from the MDS.  If that new\\n`i_nlink` value happens to be zero, it is illegal to decrement it\\nfurther.  But that is exactly what ceph_unlink() will do then.\\n\\nThe WARNING can be reproduced this way:\\n\\n1. Force async unlink; only the async code path is affected.  Having\\n   no real clue about Ceph internals, I was unable to find out why the\\n   MDS wouldn\u0027t give me the \\\"Fxr\\\" capabilities, so I patched\\n   get_caps_for_async_unlink() to always succeed.\\n\\n   (Note that the WARNING dump above was found on an unpatched kernel,\\n   without this kludge - this is not a theoretical bug.)\\n\\n2. Add a sleep call after ceph_mdsc_submit_request() so the unlink\\n   completion gets handled by a worker thread before drop_nlink() is\\n   called.  This guarantees that the `i_nlink` is already zero before\\n   drop_nlink() runs.\\n\\nThe solution is to skip the counter decrement when it is already zero,\\nbut doing so without a lock is still racy (TOCTOU).  Since\\nceph_fill_inode() and handle_cap_grant() both hold the\\n`ceph_inode_info.i_ceph_lock` spinlock while set_nlink() runs, this\\nseems like the proper lock to protect the `i_nlink` updates.\\n\\nI found prior art in NFS and SMB (using `inode.i_lock`) and AFS (using\\n`afs_vnode.cb_lock`).  All three have the zero check as well.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/ceph/dir.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"2ccb45462aeaf0831397b90d31d3d50a7704fa1f\",\"lessThan\":\"9b31e88ac5623d15c8bc46f69dfe1d3b43a8f67c\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2ccb45462aeaf0831397b90d31d3d50a7704fa1f\",\"lessThan\":\"6d5fd8bb574bef039eb3b738e523870433a2aeb9\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2ccb45462aeaf0831397b90d31d3d50a7704fa1f\",\"lessThan\":\"fcc477a6e8856c8a42b3c9e171724d8d6dfadd06\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2ccb45462aeaf0831397b90d31d3d50a7704fa1f\",\"lessThan\":\"b3f5513141ecc6b277a8f7b7efe58a0cf9a5e859\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2ccb45462aeaf0831397b90d31d3d50a7704fa1f\",\"lessThan\":\"aedd29386b23f3e1e6818943e11abfff2953732f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2ccb45462aeaf0831397b90d31d3d50a7704fa1f\",\"lessThan\":\"7db008e85a5d17b64bc5390b828bf457ae91a415\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2ccb45462aeaf0831397b90d31d3d50a7704fa1f\",\"lessThan\":\"8975b85b0d45ca811ace6fac5907652f2310e5ac\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2ccb45462aeaf0831397b90d31d3d50a7704fa1f\",\"lessThan\":\"ce0123cbb4a40a2f1bbb815f292b26e96088639f\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/ceph/dir.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.7\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.7\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.253\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.203\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.167\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.130\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.78\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.19\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.19.9\",\"lessThanOrEqual\":\"6.19.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":4.7,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.0,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-367\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.7\",\"versionEndExcluding\":\"5.10.253\",\"matchCriteriaId\":\"0B1A046E-0C62-426C-8D6D-9BCC6EB56D6E\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.11\",\"versionEndExcluding\":\"5.15.203\",\"matchCriteriaId\":\"20DDB3E9-AABF-4107-ADB0-5362AA067045\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.16\",\"versionEndExcluding\":\"6.1.167\",\"matchCriteriaId\":\"2EDC6BAF-B710-4E26-B6AA-D68922EE7B43\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.2\",\"versionEndExcluding\":\"6.6.130\",\"matchCriteriaId\":\"C57BB918-DF28-46B3-94F7-144176841267\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.12.78\",\"matchCriteriaId\":\"28D591F5-B196-4CC9-905C-DC80F116E7A8\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.18.19\",\"matchCriteriaId\":\"D394AC60-6F28-435F-872A-CCDF384B8331\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.19\",\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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-06-28T11:51:48+00:00",
      "cve": "CVE-2026-43420",
      "id": "CVE-2026-43420",
      "initial_release_date": "2026-05-08T00:00:00+00:00",
      "product_status:known_affected": "232",
      "product_status:known_not_affected": "42",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ceph: fix i_nlink underrun during async unlink",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43420.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.