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Fencer Vulns
critical 9.8

CVE-2026-53176 in the critical feed json

IB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN

published 2026-06-25 4 mo ago modified 2026-10-19 20 d ago also EUVD-2026-39267

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 55%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, 6.18.36, 7.0.13, 7.1
  • Red Hat Red Hat Enterprise Linux 10 0:6.12.0-211.56.1.el10_2
  • Red Hat Red Hat Enterprise Linux 8 0:4.18.0-553.164.1.el8_10, 0:4.18.0-553.164.1.rt7.505.el8_10
  • Red Hat Red Hat Enterprise Linux 9 0:5.14.0-687.49.1.el9_8
  • linux Debian 12 6.1.176-1
  • linux Debian 13 6.12.94-1
  • linux Debian 14 7.0.13-1

debian advisories DEBIAN-CVE-2026-53176

  • linux Ubuntu 22.04 LTS 5.15.0-187.197
  • linux Ubuntu 24.04 LTS 6.8.0-137.137
  • linux Ubuntu 26.04 LTS 7.0.0-29.29
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1113.120
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1062.65
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1010.10
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1114.124
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1065.73

ubuntu advisories UBUNTU-CVE-2026-53176

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 9 5.14.0-687.49.1.el9_8
  • rv RHEL 9 5.14.0-687.49.1.el9_8
  • perf RHEL 9 5.14.0-687.49.1.el9_8
  • rtla RHEL 9 5.14.0-687.49.1.el9_8
  • libperf RHEL 9 5.14.0-687.49.1.el9_8
  • kernel-rt RHEL 9 5.14.0-687.49.1.el9_8
  • kernel-64k RHEL 9 5.14.0-687.49.1.el9_8
  • kernel-core RHEL 9 5.14.0-687.49.1.el9_8

red hat advisories RHSA-2026:68570RHSA-2026:68531RHSA-2026:68507RHSA-2026:68532

  • kernel-source Linux Micro 6.1, Linux Micro 6.0 6.4.0-50.2
  • kernel-default Linux Micro 6.1, Linux Micro 6.0 6.4.0-50.1
  • kernel-kvmsmall Linux Micro 6.1, Linux Micro 6.0 6.4.0-50.1
  • kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-50.1
  • kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-50.2
  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.73.2
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.73.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.73.2

suse advisories SUSE-SU-2026:3594-1SUSE-SU-2026:22810-1SUSE-SU-2026:22809-1SUSE-SU-2026:22904-1SUSE-SU-2026:22903-1SUSE-SU-2026:3166-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.36.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.36.1

opensuse advisories openSUSE-SU-2026:21388-1

  • kernel AlmaLinux 10 6.12.0-211.56.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.56.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.56.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.56.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.56.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.56.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.56.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.56.1.el10_2

almalinux advisories ALSA-2026:68507ALSA-2026:68531ALSA-2026:68532ALSA-2026:68570

  • kernel Rocky Linux 10 6.12.0-211.56.1.el10_2.0.1
  • kernel Rocky Linux 9 5.14.0-687.49.1.el9_8
  • kernel-rt Rocky Linux 8 4.18.0-553.164.1.rt7.505.el8_10
  • kernel Rocky Linux 8 4.18.0-553.164.1.el8_10

rocky linux advisories RLSA-2026:68507RLSA-2026:68570RLSA-2026:68532RLSA-2026:68531

  • kernel Azure Linux 3.0 6.6.143.1-1

azure linux advisories AZL-90474

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-53176 updated cvss 6.5

kernel: IB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN

  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: workaround, no fix available “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.”
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.49.1.el9_8, perf 5.14.0-687.49.1.el9_8, rtla 5.14.0-687.49.1.el9_8, python3-perf 5.14.0-687.49.1.el9_8, kernel-devel-matched 5.14.0-687.49.1.el9_8, kernel-64k-devel-matched 5.14.0-687.49.1.el9_8, +7 more
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68570
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.56.1.el10_2, perf 6.12.0-211.56.1.el10_2, rtla 6.12.0-211.56.1.el10_2, python3-perf 6.12.0-211.56.1.el10_2, kernel-devel-matched 6.12.0-211.56.1.el10_2, kernel-64k-devel-matched 6.12.0-211.56.1.el10_2, +7 more
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68507
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.164.1.el8_10, kernel 4.18.0-553.164.1.el8_10, bpftool 4.18.0-553.164.1.el8_10, kernel-core 4.18.0-553.164.1.el8_10, kernel-tools 4.18.0-553.164.1.el8_10, python3-perf 4.18.0-553.164.1.el8_10, +15 more
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68531
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.49.1.el9_8, kernel-64k 5.14.0-687.49.1.el9_8, kernel-core 5.14.0-687.49.1.el9_8, kernel-tools 5.14.0-687.49.1.el9_8, kernel-modules 5.14.0-687.49.1.el9_8, kernel-64k-core 5.14.0-687.49.1.el9_8, +27 more
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68570
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.56.1.el10_2, kernel-64k 6.12.0-211.56.1.el10_2, kernel-core 6.12.0-211.56.1.el10_2, kernel-tools 6.12.0-211.56.1.el10_2, kernel-modules 6.12.0-211.56.1.el10_2, kernel-64k-core 6.12.0-211.56.1.el10_2, +28 more
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68507
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.49.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.49.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.49.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.49.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.49.1.el9_8
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68570
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.56.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.56.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.56.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.56.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.56.1.el10_2
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68507
show 8 more
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.164.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.164.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.164.1.el8_10
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68531
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.164.1.rt7.505.el8_10, kernel-rt-kvm 4.18.0-553.164.1.rt7.505.el8_10, kernel-rt-core 4.18.0-553.164.1.rt7.505.el8_10, kernel-rt-modules 4.18.0-553.164.1.rt7.505.el8_10, kernel-rt-debug-kvm 4.18.0-553.164.1.rt7.505.el8_10, kernel-rt-debug-core 4.18.0-553.164.1.rt7.505.el8_10, +4 more
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68532
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.49.1.el9_8, kernel-rt-64k 5.14.0-687.49.1.el9_8, kernel-rt-core 5.14.0-687.49.1.el9_8, kernel-rt-modules 5.14.0-687.49.1.el9_8, kernel-rt-64k-core 5.14.0-687.49.1.el9_8, kernel-rt-debug-core 5.14.0-687.49.1.el9_8, +14 more
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68570
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.56.1.el10_2, kernel-rt-64k 6.12.0-211.56.1.el10_2, kernel-rt-core 6.12.0-211.56.1.el10_2, kernel-rt-modules 6.12.0-211.56.1.el10_2, kernel-rt-64k-core 6.12.0-211.56.1.el10_2, kernel-rt-debug-core 6.12.0-211.56.1.el10_2, +14 more
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68507
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.49.1.el9_8, kernel-rt-core 5.14.0-687.49.1.el9_8, kernel-rt-modules 5.14.0-687.49.1.el9_8, kernel-rt-debug-core 5.14.0-687.49.1.el9_8, kernel-rt-modules-core 5.14.0-687.49.1.el9_8, kernel-rt-debug-modules 5.14.0-687.49.1.el9_8, +4 more
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68570
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.56.1.el10_2, kernel-rt-core 6.12.0-211.56.1.el10_2, kernel-rt-modules 6.12.0-211.56.1.el10_2, kernel-rt-debug-core 6.12.0-211.56.1.el10_2, kernel-rt-modules-core 6.12.0-211.56.1.el10_2, kernel-rt-debug-modules 6.12.0-211.56.1.el10_2, +4 more
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68507
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.164.1.rt7.505.el8_10, kernel-rt-core 4.18.0-553.164.1.rt7.505.el8_10, kernel-rt-modules 4.18.0-553.164.1.rt7.505.el8_10, kernel-rt-debug-core 4.18.0-553.164.1.rt7.505.el8_10, kernel-rt-debug-modules 4.18.0-553.164.1.rt7.505.el8_10, kernel-rt-modules-extra 4.18.0-553.164.1.rt7.505.el8_10, +2 more
    fixed: vendor fix “To mitigate this issue, prevent module ib_isert from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2026:68532
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
23 d ago

Exploit prediction

0.76% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADP 3.1 6.5 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 6.5 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7

Classification

Weakness
  • CWE-839 Numeric Range Comparison Without Minimum Check
  • CWE-191 Integer Underflow (Wrap or Wraparound)
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.