CVE-2026-89607 (GCVE-0-2026-89607)
Vulnerability from cvelistv5
Published
2026-09-11 19:45
Modified
2026-10-19 08:49
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ecryptfs: reject oversized encrypted_key_size in parse_tag_3_packet parse_tag_3_packet() set encrypted_key_size from the Tag 3 packet body without bounding it against ECRYPTFS_MAX_KEY_BYTES (64). When encrypted_key_size > 64, decrypt_passphrase_encrypted_session_key() sets decrypted_key_size = encrypted_key_size and performs two out-of-bounds writes: 1. crypto_skcipher_decrypt() writes encrypted_key_size bytes into decrypted_key[64] via scatterlist, overflowing into the parent ecryptfs_auth_tok struct. 2. memcpy(crypt_stat->key, decrypted_key, decrypted_key_size) writes into crypt_stat->key[64], corrupting root_iv, keysig_list, and mutexes in ecryptfs_crypt_stat. Only AES-192 (cipher code 0x08) enables this because it sets crypt_stat->key_size = 24 independently of encrypted_key_size, allowing crypto_skcipher_setkey() to succeed while encrypted_key_size exceeds ECRYPTFS_MAX_KEY_BYTES. The PKI decryption path (parse_tag_65_packet) already validates decrypted_key_size <= ECRYPTFS_MAX_KEY_BYTES; the passphrase path omits this check. Bound encrypted_key_size against ECRYPTFS_MAX_KEY_BYTES (64) rather than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES (512). The 64-byte limit also protects the 512-byte encrypted_key[] buffer, so the former 512-byte check is removed as redundant. [tyhicks: Adjust the code comment to refer to macros representing the buffer sizes rather than mentioning the buffer size values since they may change in the future]
References
Impacted products
Vendor Product Version
Linux Linux Version: 237fead619984cc48818fe12ee0ceada3f55b012
Version: 237fead619984cc48818fe12ee0ceada3f55b012
Version: 237fead619984cc48818fe12ee0ceada3f55b012
Version: 237fead619984cc48818fe12ee0ceada3f55b012
Version: 237fead619984cc48818fe12ee0ceada3f55b012
Version: 237fead619984cc48818fe12ee0ceada3f55b012
Version: 237fead619984cc48818fe12ee0ceada3f55b012
Version: 237fead619984cc48818fe12ee0ceada3f55b012
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ecryptfs/keystore.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
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              "status": "affected",
              "version": "237fead619984cc48818fe12ee0ceada3f55b012",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "237fead619984cc48818fe12ee0ceada3f55b012",
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            },
            {
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              "status": "affected",
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              "versionType": "git"
            },
            {
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            {
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/ecryptfs/keystore.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.19"
            },
            {
              "lessThan": "2.6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.270",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.221",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.270",
                  "versionStartIncluding": "2.6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.221",
                  "versionStartIncluding": "2.6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.188",
                  "versionStartIncluding": "2.6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.157",
                  "versionStartIncluding": "2.6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.109",
                  "versionStartIncluding": "2.6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "2.6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "2.6.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\necryptfs: reject oversized encrypted_key_size in parse_tag_3_packet\n\nparse_tag_3_packet() set encrypted_key_size from the Tag 3 packet body\nwithout bounding it against ECRYPTFS_MAX_KEY_BYTES (64). When\nencrypted_key_size \u003e 64, decrypt_passphrase_encrypted_session_key()\nsets decrypted_key_size = encrypted_key_size and performs two\nout-of-bounds writes:\n\n1. crypto_skcipher_decrypt() writes encrypted_key_size bytes into\n   decrypted_key[64] via scatterlist, overflowing into the parent\n   ecryptfs_auth_tok struct.\n2. memcpy(crypt_stat-\u003ekey, decrypted_key, decrypted_key_size) writes\n   into crypt_stat-\u003ekey[64], corrupting root_iv, keysig_list, and\n   mutexes in ecryptfs_crypt_stat.\n\nOnly AES-192 (cipher code 0x08) enables this because it sets\ncrypt_stat-\u003ekey_size = 24 independently of encrypted_key_size,\nallowing crypto_skcipher_setkey() to succeed while encrypted_key_size\nexceeds ECRYPTFS_MAX_KEY_BYTES.\n\nThe PKI decryption path (parse_tag_65_packet) already validates\ndecrypted_key_size \u003c= ECRYPTFS_MAX_KEY_BYTES; the passphrase path\nomits this check.\n\nBound encrypted_key_size against ECRYPTFS_MAX_KEY_BYTES (64) rather\nthan ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES (512). The 64-byte limit also\nprotects the 512-byte encrypted_key[] buffer, so the former 512-byte\ncheck is removed as redundant.\n\n[tyhicks: Adjust the code comment to refer to macros representing the\n buffer sizes rather than mentioning the buffer size values since they\n may change in the future]"
        }
      ],
      "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": [
            {
              "lang": "en",
              "value": "AV:L - Triggered by a local open/setattr on an eCryptfs mount: ecryptfs_open -\u003e read_or_initialize_metadata -\u003e ecryptfs_read_metadata parses attacker-supplied Tag 3 packets from the lower file header (or xattr). The kernel does not process this as network protocol data.\nAC:L - The attacker fully controls the Tag 3 body, including AES-192 cipher code 0x08 and an AES-block-aligned encrypted_key_size of 80-512 bytes. decrypt_passphrase_encrypted_session_key() then overflows deterministically; no race or uninfluenced memory layout is required to trigger the writes.\nPR:L - An unprivileged user reaches this on standard eCryptfs deployments (setuid-root mount.ecryptfs_private and per-user encrypted home/Private). They plant a crafted lower file under their own .Private directory and open it through the already-mounted eCryptfs tree; init-namespace root is not required.\nUI:N - The attacker performs the whole sequence themselves: install a matching passphrase auth token, write the malformed Tag 3/Tag 11 header into their lower directory, and open the file. No action by another user is required.\nS:U - The out-of-bounds writes corrupt kernel heap and eCryptfs inode-private objects in the same kernel security authority. This is local privilege escalation, not a VM, IOMMU, or sandbox boundary crossing.\nC:H - crypto_skcipher_decrypt() and memcpy() write tens to hundreds of bytes past decrypted_key[64] and crypt_stat-\u003ekey[64], overflowing into reserved/token fields, keysig_list, mutexes, and adjacent slab/inode-cache objects. That heap corruption can be groomed into an arbitrary kernel read.\nI:H - Session-key wrap uses AES-ECB with the attacker\u0027s known passphrase-derived key, so the overflow payload is chosen plaintext. Up to 448 bytes past the 64-byte buffers corrupt list_head pointers and neighboring slab objects, yielding a write primitive for control-flow hijack.\nA:H - Corrupting keysig_list, embedded mutexes, and adjacent inode-cache/slab objects causes kernel oops or panic. The attacker can open the crafted file repeatedly to crash the system at will."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:49:39.398Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/2cd21340163494d312836c77c9fbfe2530b3d075"
        },
        {
          "url": "https://git.kernel.org/stable/c/e2152d491ae62d96a32ed59778680a242af1fbc6"
        },
        {
          "url": "https://git.kernel.org/stable/c/d2802414081184f79a619ede178aeef3aa989793"
        },
        {
          "url": "https://git.kernel.org/stable/c/33e050cac841498b5175f0f385eee903fd98863c"
        },
        {
          "url": "https://git.kernel.org/stable/c/ccd13eff0e7356d2aa28b127b577e4e5ad4563f5"
        },
        {
          "url": "https://git.kernel.org/stable/c/14cb36a500a5a3afbc955dbf69dabc565f1a3b26"
        },
        {
          "url": "https://git.kernel.org/stable/c/a419c9ebfc9a40ee56aaad6dc68bfd67d400817b"
        },
        {
          "url": "https://git.kernel.org/stable/c/5babe9c177c364521e3e682b949c5a8c47f4a441"
        }
      ],
      "title": "ecryptfs: reject oversized encrypted_key_size in parse_tag_3_packet",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89607",
    "datePublished": "2026-09-11T19:45:09.583Z",
    "dateReserved": "2026-09-11T19:38:34.733Z",
    "dateUpdated": "2026-10-19T08:49:39.398Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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