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CVE-2026-53176

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: IB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN In drivers/infiniband/ulp/isert/ib_isert.c, isert_login_recv_done() computes the login request payload length as wc->byte_len minus ISER_HEADERS_LEN with no lower bound, and login_req_len is a signed int. A remote iSER initiator can post a login Send work request carrying fewer than ISER_HEADERS_LEN (76) bytes, so the subtraction underflows and login_req_len becomes negative. isert_rx_login_req() then reads that negative length back into a signed int, takes size = min(rx_buflen, MAX_KEY_VALUE_PAIRS), and because the min() is signed it keeps the negative value; the value is then passed as the memcpy() length and sign-extended to a multi-gigabyte size_t. The copy into the 8192-byte login->req_buf runs far out of bounds and faults, crashing the target node. The login phase precedes iSCSI authentication, so no credentials are required to reach this path. Reject any login PDU shorter than ISER_HEADERS_LEN before the subtraction, mirroring the existing early return on a failed work completion, so login_req_len can never go negative. The upper bound was already safe: a posted login buffer cannot deliver more than ISER_RX_PAYLOAD_SIZE, so the difference stays at or below MAX_KEY_VALUE_PAIRS and the existing min() clamps it; only the missing lower bound needs to be added.

Severity
CRITICAL
CVSS score
9.8 (v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-06-25 09:16:34.953000
Last modified
2026-10-19 20:19:06.103000
View original CVE JSON 
{
  "id": "CVE-2026-53176",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-06-25T09:16:34.953",
  "lastModified": "2026-10-19T20:19:06.103",
  "vulnStatus": "Modified",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nIB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN\n\nIn drivers/infiniband/ulp/isert/ib_isert.c, isert_login_recv_done()\ncomputes the login request payload length as wc->byte_len minus\nISER_HEADERS_LEN with no lower bound, and login_req_len is a signed int.\nA remote iSER initiator can post a login Send work request carrying\nfewer than ISER_HEADERS_LEN (76) bytes, so the subtraction underflows\nand login_req_len becomes negative.\n\nisert_rx_login_req() then reads that negative length back into a signed\nint, takes size = min(rx_buflen, MAX_KEY_VALUE_PAIRS), and because the\nmin() is signed it keeps the negative value; the value is then passed as\nthe memcpy() length and sign-extended to a multi-gigabyte size_t. The\ncopy into the 8192-byte login->req_buf runs far out of bounds and\nfaults, crashing the target node. The login phase precedes iSCSI\nauthentication, so no credentials are required to reach this path.\n\nReject any login PDU shorter than ISER_HEADERS_LEN before the\nsubtraction, mirroring the existing early return on a failed work\ncompletion, so login_req_len can never go negative. The upper bound was\nalready safe: a posted login buffer cannot deliver more than\nISER_RX_PAYLOAD_SIZE, so the difference stays at or below\nMAX_KEY_VALUE_PAIRS and the existing min() clamps it; only the missing\nlower bound needs to be added."
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