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CVE-2026-80961 (GCVE-0-2026-80961)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:42 – Updated: 2026-09-13 06:28
VLAI
Title
dm-pcache: validate kset key_num and intra-segment bounds
Summary
In the Linux kernel, the following vulnerability has been resolved: dm-pcache: validate kset key_num and intra-segment bounds Two more fields decoded from the cache device go unbounded. The kset key_num drives cache_kset_crc() and the replay loop in cache_replay(), the writeback worker and the GC worker, but only the magic and a fixed-seed CRC are checked first, so a non-last kset whose key_num exceeds the PCACHE_KSET_KEYS_MAX buffer reads past its end before the CRC compare. A key's intra-segment offset and length in cache_key_decode() are taken verbatim, so a key running past its segment is replayed into the cache tree and the data CRC check and every later read hit then copy adjacent persistent memory into the caller's bio -- an out-of-bounds read that leaks to user space. Both fields are controlled by whoever supplies the cache device (CAP_SYS_ADMIN); the CRC seed is public. Add kset_onmedia_valid() to bound key_num before any kset read, and reject a key whose offset plus length, computed in 64 bits, exceeds the segment data_size. Valid metadata is unaffected.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 , < d8caf96040a06096276ab72f5e1e8547c014c564 (git)
Affected: 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 , < 5ac38f4b4862fad6e7270fde5c3356a822ce74ca (git)
Affected: 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 , < f11deb032fd84081e7831cffcba895d893054a22 (git)
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Linux Linux Affected: 6.18
Unaffected: 0 , < 6.18 (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/md/dm-pcache/cache.h",
            "drivers/md/dm-pcache/cache_gc.c",
            "drivers/md/dm-pcache/cache_key.c",
            "drivers/md/dm-pcache/cache_writeback.c"
          ],
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              "version": "1d57628ff95b32d5cfa8d8f50e07690c161e9cf0",
              "versionType": "git"
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              "status": "affected",
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              "versionType": "git"
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        {
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          "product": "Linux",
          "programFiles": [
            "drivers/md/dm-pcache/cache.h",
            "drivers/md/dm-pcache/cache_gc.c",
            "drivers/md/dm-pcache/cache_key.c",
            "drivers/md/dm-pcache/cache_writeback.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "6.18"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm-pcache: validate kset key_num and intra-segment bounds\n\nTwo more fields decoded from the cache device go unbounded. The kset\nkey_num drives cache_kset_crc() and the replay loop in cache_replay(),\nthe writeback worker and the GC worker, but only the magic and a\nfixed-seed CRC are checked first, so a non-last kset whose key_num exceeds\nthe PCACHE_KSET_KEYS_MAX buffer reads past its end before the CRC compare.\nA key\u0027s intra-segment offset and length in cache_key_decode() are taken\nverbatim, so a key running past its segment is replayed into the cache\ntree and the data CRC check and every later read hit then copy adjacent\npersistent memory into the caller\u0027s bio -- an out-of-bounds read that\nleaks to user space. Both fields are controlled by whoever supplies the\ncache device (CAP_SYS_ADMIN); the CRC seed is public.\n\nAdd kset_onmedia_valid() to bound key_num before any kset read, and\nreject a key whose offset plus length, computed in 64 bits, exceeds the\nsegment data_size. Valid metadata is unaffected."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
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              "lang": "en",
              "value": "AV:L - The bugs are reached only via local device-mapper ioctls on /dev/mapper/control (ctl_ioctl \u2192 table_load \u2192 dm_pcache_ctr \u2192 pcache_cache_start \u2192 cache_replay) and the subsequent local GC/writeback workers and bio map path; no network protocol or physical-bus input feeds kset/key decode.\nAC:L - The attacker fully controls the DAX cache image; kset CRC uses public PCACHE_CRC_SEED 0x3B15A, so a non-last kset with key_num \u003e 128 and keys whose cache_seg_off+len exceed the segment are encoded and replayed deterministically on table load with no race or victim-side state.\nPR:L - ctl_ioctl gates DM_TABLE_LOAD with capable(CAP_SYS_ADMIN), which per kernel CNA guidance is obtainable inside an unprivileged user namespace and in storage containers with delegated mapper/DAX nodes, so this is Low rather than init-namespace root only.\nUI:N - Exploitation requires only the attacker\u0027s own dmsetup/DM_TABLE_LOAD of a pcache target whose cache device holds crafted INIT_DONE ksets, then optional reads of the mapped device; no separate victim must mount media or open files.\nS:U - The out-of-bounds kset/key access corrupts and discloses memory inside the host kernel that loaded the pcache table; it does not cross a VM, hypervisor, IOMMU, or other separate security-authority boundary.\nC:H - cache_kset_crc() reads struct_size(..., key_num) bytes from a buffer sized for 128 keys, an unbounded kernel-heap OOB read; keys with unchecked cache_seg_off+len are then copied by segment_copy_to_bio() from adjacent pmem/kernel memory into the caller\u0027s bio, leaking to userspace.\nI:H - Replay inserts those OOB keys into the cache tree; writeback then copies from the attacker-chosen cache addresses onto the backing device, and later cut/advance of those keys operates on corrupted cache_pos. This OOB memory-corruption class is Integrity High under kernel CNA guidance.\nA:H - An oversized key_num makes crc32c walk off the kset buffer into unmapped heap, writeback BUG_ON(seg_remain \u003c key-\u003elen), and cache_pos_advance() BUG_ON or a copy past the DAX mapping can oops or panic the kernel, causing system-wide denial of service."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-13T06:28:32.873Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/d8caf96040a06096276ab72f5e1e8547c014c564"
        },
        {
          "url": "https://git.kernel.org/stable/c/5ac38f4b4862fad6e7270fde5c3356a822ce74ca"
        },
        {
          "url": "https://git.kernel.org/stable/c/f11deb032fd84081e7831cffcba895d893054a22"
        }
      ],
      "title": "dm-pcache: validate kset key_num and intra-segment bounds",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80961",
    "datePublished": "2026-09-11T19:42:27.847Z",
    "dateReserved": "2026-08-26T14:34:25.809Z",
    "dateUpdated": "2026-09-13T06:28:32.873Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-09-18",
      "epss": "0.00161",
      "percentile": "0.05769"
    },
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      "cve": {
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                "product": "Linux",
                "programFiles": [
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                  "drivers/md/dm-pcache/cache_gc.c",
                  "drivers/md/dm-pcache/cache_key.c",
                  "drivers/md/dm-pcache/cache_writeback.c"
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                    "versionType": "git"
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm-pcache: validate kset key_num and intra-segment bounds\n\nTwo more fields decoded from the cache device go unbounded. The kset\nkey_num drives cache_kset_crc() and the replay loop in cache_replay(),\nthe writeback worker and the GC worker, but only the magic and a\nfixed-seed CRC are checked first, so a non-last kset whose key_num exceeds\nthe PCACHE_KSET_KEYS_MAX buffer reads past its end before the CRC compare.\nA key\u0027s intra-segment offset and length in cache_key_decode() are taken\nverbatim, so a key running past its segment is replayed into the cache\ntree and the data CRC check and every later read hit then copy adjacent\npersistent memory into the caller\u0027s bio -- an out-of-bounds read that\nleaks to user space. Both fields are controlled by whoever supplies the\ncache device (CAP_SYS_ADMIN); the CRC seed is public.\n\nAdd kset_onmedia_valid() to bound key_num before any kset read, and\nreject a key whose offset plus length, computed in 64 bits, exceeds the\nsegment data_size. Valid metadata is unaffected."
          }
        ],
        "id": "CVE-2026-80961",
        "lastModified": "2026-09-13T07:17:03.070",
        "metrics": {
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                "attackVector": "LOCAL",
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                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
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              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-09-11T20:19:01.980",
        "references": [
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          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-14T08:59:42+00:00",
      "cve": "CVE-2026-80961",
      "id": "CVE-2026-80961",
      "initial_release_date": "2026-09-11T00:00:00+00:00",
      "product_status:known_not_affected": "276",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: dm-pcache: validate kset key_num and intra-segment bounds",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80961.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-15T01:05:22Z",
      "cve": "CVE-2026-80961",
      "id": "CVE-2026-80961",
      "initial_release_date": "2026-09-15T01:05:22Z",
      "product_status:known_not_affected": "353",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-80961",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-80961.json",
      "version": "2"
    }
  }
}



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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

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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.


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