CVE-2026-90011 (GCVE-0-2026-90011)
Vulnerability from cvelistv5
Published
2026-09-16 10:33
Modified
2026-10-19 08:56
Severity ?
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: scsi: target: iscsi: Reserve a terminator byte for the login payload iscsi_target_check_login_request() rejects a login PDU whose DataSegmentLength exceeds MAX_KEY_VALUE_PAIRS, but the test is '>' and login->req_buf is allocated with exactly MAX_KEY_VALUE_PAIRS bytes. Since iscsit_get_login_rx() receives payload_length + padding bytes, where padding = ((-payload_length) & 3); any payload_length from 8189 to 8192 fills the whole 8192 byte buffer. The write stays in bounds, but no byte is left for a NUL terminator. The buffer is subsequently consumed as a C string. In the CHAP path chap_check_algorithm() calls kstrdup(a_str), and extract_param() calls strstr(in_buf, pattern) followed by strlen_semi(), none of which take a length. convert_null_to_semi() additionally rewrites every embedded NUL to ';', so even a payload made of well formed NUL separated key=value records is left without a terminator. These walk past the end of the object into adjacent slab memory. It is reachable by an unauthenticated initiator against a portal configured for CHAP; when authentication is not required iscsi_login_zero_tsih_s2() rewrites AuthMethod to None and the CHAP path is never entered. Allocate one extra byte. kzalloc() zeroes it and nothing ever writes to it, as every writer copies to offset 0 for at most MAX_KEY_VALUE_PAIRS bytes, so the buffer is always terminated.
References
Impacted products
Vendor Product Version
Linux Linux Version: e48354ce078c079996f89d715dfa44814b4eba01
Version: e48354ce078c079996f89d715dfa44814b4eba01
Version: e48354ce078c079996f89d715dfa44814b4eba01
Version: e48354ce078c079996f89d715dfa44814b4eba01
Version: e48354ce078c079996f89d715dfa44814b4eba01
Version: e48354ce078c079996f89d715dfa44814b4eba01
Version: e48354ce078c079996f89d715dfa44814b4eba01
Version: e48354ce078c079996f89d715dfa44814b4eba01
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/target/iscsi/iscsi_target_login.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/target/iscsi/iscsi_target_login.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.1"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
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              "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": "6.12.110",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "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": "3.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "3.1",
                  "vulnerable": true
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.188",
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                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.157",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.110",
                  "versionStartIncluding": "3.1",
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "3.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.5",
                  "versionStartIncluding": "3.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "3.1",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: target: iscsi: Reserve a terminator byte for the login payload\n\niscsi_target_check_login_request() rejects a login PDU whose\nDataSegmentLength exceeds MAX_KEY_VALUE_PAIRS, but the test is \u0027\u003e\u0027 and\nlogin-\u003ereq_buf is allocated with exactly MAX_KEY_VALUE_PAIRS\nbytes. Since iscsit_get_login_rx() receives payload_length + padding\nbytes, where\n\n\tpadding = ((-payload_length) \u0026 3);\n\nany payload_length from 8189 to 8192 fills the whole 8192 byte\nbuffer. The write stays in bounds, but no byte is left for a NUL\nterminator.\n\nThe buffer is subsequently consumed as a C string. In the CHAP path\nchap_check_algorithm() calls kstrdup(a_str), and extract_param() calls\nstrstr(in_buf, pattern) followed by strlen_semi(), none of which take a\nlength. convert_null_to_semi() additionally rewrites every embedded NUL\nto \u0027;\u0027, so even a payload made of well formed NUL separated key=value\nrecords is left without a terminator. These walk past the end of the\nobject into adjacent slab memory. It is reachable by an unauthenticated\ninitiator against a portal configured for CHAP; when authentication is\nnot required iscsi_login_zero_tsih_s2() rewrites AuthMethod to None and\nthe CHAP path is never entered.\n\nAllocate one extra byte. kzalloc() zeroes it and nothing ever writes to\nit, as every writer copies to offset 0 for at most MAX_KEY_VALUE_PAIRS\nbytes, so the buffer is always terminated."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The LIO in-kernel iSCSI target accepts remote TCP connections on the iSCSI portal (typically port 3260); a crafted Login PDU is received by iscsit_accept_np()/iscsit_get_login_rx() and reaches the CHAP parsers over the network, the same exposure model as nfsd or ksmbd.\nAC:L - The attacker fully controls DataSegmentLength and the login payload. A CHAP_A PDU of 8189-8192 bytes with no NUL, or a second CHAP round where convert_null_to_semi() strips every terminator, makes kstrdup()/strstr() over-read adjacent slab deterministically; no race or victim-side layout is required.\nPR:N - The over-read runs in the CHAP login handshake before the password hash is checked, so no Linux account or capability is needed. Default TPG authentication is CHAP (TA_AUTHENTICATION=1), and chap_server_open() proceeds once target-side CHAP credentials exist, which is the normal CHAP deployment.\nUI:N - The attacker opens a TCP connection to the listening portal and sends the malicious Login PDUs; no victim user action such as mounting a volume or accepting a prompt is required.\nS:U - The unbounded C-string over-read and any resulting kernel oops stay inside the host iSCSI target\u0027s kernel security authority and do not by themselves cross a VM, IOMMU, or sandbox boundary.\nC:H - chap_check_algorithm() kstrdup()s the unterminated 8192-byte req_buf, and extract_param() uses unbounded strstr()/strlen_semi() after convert_null_to_semi() removes embedded NULs, producing an unbounded out-of-bounds read of adjacent kmalloc-8k slab that can disclose neighboring kernel objects.\nI:N - iscsit_get_login_rx() copies at most MAX_KEY_VALUE_PAIRS bytes into req_buf, so the network write stays in bounds; convert_null_to_semi() also writes only within payload_length. There is no out-of-bounds write or control-flow hijack primitive.\nA:H - strlen()/kstrdup()/strstr() walking past the kmalloc-8k login object into unmapped or guard pages causes a kernel oops, and the attacker can repeat the unauthenticated login against an exposed portal, denying service to the host and its iSCSI clients."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:56:25.054Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/5fac79f248c37774d1dd761406f83d25ca6ff8e4"
        },
        {
          "url": "https://git.kernel.org/stable/c/6ddddcad436d8e6e619204d3c848147ff2f5bf1e"
        },
        {
          "url": "https://git.kernel.org/stable/c/b19dc17ed963ac36c0db4b52a1803fb11169f91f"
        },
        {
          "url": "https://git.kernel.org/stable/c/6b589ef9d5f6cdc70d2b4f269ca6cf26b5ebb076"
        },
        {
          "url": "https://git.kernel.org/stable/c/eb9dadf4d552ebe10644871c5189286552aa48f5"
        },
        {
          "url": "https://git.kernel.org/stable/c/1624bff4c5118ad494d50ad94d44f22064667a7f"
        },
        {
          "url": "https://git.kernel.org/stable/c/3ddf3ea291a0ef2ea93b82e158960ac2cc42302b"
        },
        {
          "url": "https://git.kernel.org/stable/c/f4825922d2fb371e2b969697d792077f1b62b62c"
        }
      ],
      "title": "scsi: target: iscsi: Reserve a terminator byte for the login payload",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90011",
    "datePublished": "2026-09-16T10:33:18.793Z",
    "dateReserved": "2026-09-11T19:38:34.781Z",
    "dateUpdated": "2026-10-19T08:56:25.054Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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