CVE-2026-53176Network attack vector

Unauthenticated target crash via login-length underflow

Published Jun 25, 2026 · Updated Jun 25, 2026

Numeric range error in the Linux kernel iSER target allows remote attackers to crash the target node with a short login PDU. isert_login_recv_done() subtracts the 76-byte ISER_HEADERS_LEN from wc->byte_len without a lower-bound check, and isert_rx_login_req() passes the resulting negative signed value to memcpy() as a huge size_t. An exposed RDMA/iSER target portal is required, but the login path runs before iSCSI authentication, so no credentials or user interaction are needed.

CVSS severity9.8
Critical
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Numeric range error in the Linux kernel iSER target allows remote attackers to crash the target node with a short login PDU. isert_login_recv_done() subtracts the 76-byte ISER_HEADERS_LEN from wc->byte_len without a lower-bound check, and isert_rx_login_req() passes the resulting negative signed value to memcpy() as a huge size_t. An exposed RDMA/iSER target portal is required, but the login path runs before iSCSI authentication, so no credentials or user interaction are needed.

The record

CVE
CVE-2026-53176
Published
Jun 25, 2026
Updated
Jun 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-839, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.10
  2. Affected versionversion=b8d26b3be8b33682cf163274ed07479a70554633 <1ca40b243277c9e88be5e00bd3e083f71aefb93e
  3. Affected versionversion=b8d26b3be8b33682cf163274ed07479a70554633 <29e7b925ae6df64894e82ab6419994dc25580a8a
  4. Affected versionversion=b8d26b3be8b33682cf163274ed07479a70554633 <75ee6e4aa096aa9e7b2dd5c8ff98356e30aceefb
  5. Affected versionversion=b8d26b3be8b33682cf163274ed07479a70554633 <bd22740d7f14cb1c0289444cfd2c8d2938667c1d
  6. Affected versionversion=b8d26b3be8b33682cf163274ed07479a70554633 <c1234229399f4af12c553b1b0ffd978eeba65548
  7. Affected versionversion=b8d26b3be8b33682cf163274ed07479a70554633 <c5584e089b5af7b3bf8bd5e8ca0560cbf32b0a47
  8. Affected versionversion=b8d26b3be8b33682cf163274ed07479a70554633 <df422fd273c96c2ee5beb80fc21adc8c70c29260
  9. Affected versionversion=b8d26b3be8b33682cf163274ed07479a70554633 <e8a013c0c3ca2f6708341a56612a3f6d6921620a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=3.10; version=b8d26b3be8b33682cf163274ed07479a70554633 <1ca40b243277c9e88be5e00bd3e083f71aefb93e; version=b8d26b3be8b33682cf163274ed07479a70554633 <29e7b925ae6df64894e82ab6419994dc25580a8a; version=b8d26b3be8b33682cf163274ed07479a70554633 <75ee6e4aa096aa9e7b2dd5c8ff98356e30aceefb; version=b8d26b3be8b33682cf163274ed07479a70554633 <bd22740d7f14cb1c0289444cfd2c8d2938667c1d; version=b8d26b3be8b33682cf163274ed07479a70554633 <c1234229399f4af12c553b1b0ffd978eeba65548; version=b8d26b3be8b33682cf163274ed07479a70554633 <c5584e089b5af7b3bf8bd5e8ca0560cbf32b0a47; version=b8d26b3be8b33682cf163274ed07479a70554633 <df422fd273c96c2ee5beb80fc21adc8c70c29260; version=b8d26b3be8b33682cf163274ed07479a70554633 <e8a013c0c3ca2f6708341a56612a3f6d6921620a

Published CVSS scores

6.5Red HatCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
9.8Linux kernel CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-839Numeric Range Comparison Without Minimum Check
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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