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CVE-2026-53176· NVD / CVE Program· CNA Linux

IB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN

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.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Jun 25, 2026
Updated
Sep 18, 2026
EPSS
0.8% · 54th percentile
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Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.8%

CNA vs NVD score

NVD
—
CNA · Linux
9.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel3.10 and later · before 5.10.259
  • linux linux kernel5.11 and later · before 5.15.210
  • linux linux kernel5.16 and later · before 6.1.176
  • linux linux kernel6.2 and later · before 6.6.143
  • linux linux kernel6.7 and later · before 6.12.94
  • linux linux kernel6.13 and later · before 6.18.36
  • linux linux kernel6.19 and later · before 7.0.13
  • linux linux kernel7.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 3.10affected
    • b8d26b3be8b33682cf163274ed07479a70554633 and later · before 75ee6e4aa096aa9e7b2dd5c8ff98356e30aceefbaffected · git
    • b8d26b3be8b33682cf163274ed07479a70554633 and later · before e8a013c0c3ca2f6708341a56612a3f6d6921620aaffected · git
    • b8d26b3be8b33682cf163274ed07479a70554633 and later · before bd22740d7f14cb1c0289444cfd2c8d2938667c1daffected · git
    • b8d26b3be8b33682cf163274ed07479a70554633 and later · before c1234229399f4af12c553b1b0ffd978eeba65548affected · git
    • b8d26b3be8b33682cf163274ed07479a70554633 and later · before c5584e089b5af7b3bf8bd5e8ca0560cbf32b0a47affected · git
    • b8d26b3be8b33682cf163274ed07479a70554633 and later · before df422fd273c96c2ee5beb80fc21adc8c70c29260affected · git
    • b8d26b3be8b33682cf163274ed07479a70554633 and later · before 1ca40b243277c9e88be5e00bd3e083f71aefb93eaffected · git
    • b8d26b3be8b33682cf163274ed07479a70554633 and later · before 29e7b925ae6df64894e82ab6419994dc25580a8aaffected · git
    • before 3.10not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.56.1.el10_26.12.0-211.56.1.el10_2

+96

Same product

linux: all records

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Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux1ca40b243277c9e88be5e00bd3e083f71aefb93eVendor (CNA)
Linux Linux29e7b925ae6df64894e82ab6419994dc25580a8aVendor (CNA)
Linux Linux75ee6e4aa096aa9e7b2dd5c8ff98356e30aceefbVendor (CNA)
Linux Linuxbd22740d7f14cb1c0289444cfd2c8d2938667c1dVendor (CNA)
Linux Linuxc1234229399f4af12c553b1b0ffd978eeba65548Vendor (CNA)
Linux Linuxc5584e089b5af7b3bf8bd5e8ca0560cbf32b0a47Vendor (CNA)
Linux Linuxdf422fd273c96c2ee5beb80fc21adc8c70c29260Vendor (CNA)
Linux Linuxe8a013c0c3ca2f6708341a56612a3f6d6921620aVendor (CNA)
almalinux:kernel6.12.0-211.56.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k6.12.0-211.56.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-core6.12.0-211.56.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug6.12.0-211.56.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-core6.12.0-211.56.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel6.12.0-211.56.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched6.12.0-211.56.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules6.12.0-211.56.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-core6.12.0-211.56.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra6.12.0-211.56.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel6.12.0-211.56.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel-matched6.12.0-211.56.1.el10_2 · AlmaLinux:10Package registry (OSV)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:6.12.0-211.56.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel0:6.12.0-211.56.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel-matched0:6.12.0-211.56.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debuginfo0:6.12.0-211.56.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel0:6.12.0-211.56.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel-matched0:6.12.0-211.56.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-debuginfo0:6.12.0-211.56.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-devel0:6.12.0-211.56.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-devel-matched0:6.12.0-211.56.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)

+5

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-4318750 days apartxfs: delete attr leaf freemap entries when empty
    35Monitor
  • CVE-2026-531780 days apartstaging: rtl8723bs: rtw_mlme: add bounds checks before ie_length subtraction
    32Monitor
  • CVE-2026-529191 days apartbatman-adv: fix tp_meter counter underflow during shutdown
    31Monitor
  • CVE-2026-531301 days apartfs/omfs: reject s_sys_blocksize smaller than OMFS_DIR_START
    31Monitor
  • CVE-2026-4610728 days apartdm-thin: fix metadata refcount underflow
    31Monitor
  • CVE-2026-6436130 days aparthfs/hfsplus: fix u32 overflow in check_and_correct_requested_length
    31Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-191 · Integer Underflow (Wrap or Wraparound)

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records