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CVE-2026-53176

IB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN

Critical9.8EPSS 0.76%
Published
Updated
Reserved
Assigned by
Linux

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.

Scores

CVSS scores of CVE-2026-53176, by who scored it
Scored byCVSSScoreVector
LinuxCNA (assigner)3.1Critical9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
redhat-SADPADP (enrichment)3.1Medium6.5CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVDNVD · Modified3.1Critical9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (exploitation in 30 days)
0.76% · top 45% of all CVEs (6 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: yes · Technical impact: total
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.

Weakness

Affected products

  • Linux · Linux

    • affected b8d26b3be8b33682cf163274ed07479a70554633 – < 75ee6e4aa096aa9e7b2dd5c8ff98356e30aceefb
    • affected b8d26b3be8b33682cf163274ed07479a70554633 – < e8a013c0c3ca2f6708341a56612a3f6d6921620a
    • affected b8d26b3be8b33682cf163274ed07479a70554633 – < bd22740d7f14cb1c0289444cfd2c8d2938667c1d
    • affected b8d26b3be8b33682cf163274ed07479a70554633 – < c1234229399f4af12c553b1b0ffd978eeba65548
    • affected b8d26b3be8b33682cf163274ed07479a70554633 – < c5584e089b5af7b3bf8bd5e8ca0560cbf32b0a47
    • affected b8d26b3be8b33682cf163274ed07479a70554633 – < df422fd273c96c2ee5beb80fc21adc8c70c29260
    • affected b8d26b3be8b33682cf163274ed07479a70554633 – < 1ca40b243277c9e88be5e00bd3e083f71aefb93e
    • affected b8d26b3be8b33682cf163274ed07479a70554633 – < 29e7b925ae6df64894e82ab6419994dc25580a8a

  • Linux · Linux

    • affected 3.10
    • unaffected < 3.10
    • unaffected 5.10.259 – ≤ 5.10.*
    • unaffected 5.15.210 – ≤ 5.15.*
    • unaffected 6.1.176 – ≤ 6.1.*
    • unaffected 6.6.143 – ≤ 6.6.*
    • unaffected 6.12.94 – ≤ 6.12.*
    • unaffected 6.18.36 – ≤ 6.18.*
    • unaffected 7.0.13 – ≤ 7.0.*
    • unaffected 7.1 – ≤ *

References (15)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .