CVE-2026-53176 | 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.

Published: 2026-06-25 Last update: 2026-07-14 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-53176 is rated Moderate Risk (57/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 0.74%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-53176

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-07-03 0.40% 0.74% +0.34%
2 2026-06-30 0.60% 0.40% -0.20%
3 2026-06-28 — 0.60% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-53176

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 416baaa9-dc9f-4396-8d5f-8c081fb06d67
6.5 3.1 MEDIUM
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

Weakness enumeration for CVE-2026-53176

GitHub Security Advisory for CVE-2026-53176

GHSA-cm56-mvx6-66qm · Severity: critical — In the Linux kernel, the following vulnerability has been resolved: IB/isert: Reject login PDUs...

OS Trackers for CVE-2026-53176

vendor priority summary link
debian not yet assigned CVE-2026-53176 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. https://security-tracker.debian.org/tracker/CVE-2026-53176
redhat high — https://access.redhat.com/security/cve/CVE-2026-53176
suse high CVE-2026-53176 severity important: SUSE including 4 source package names (kernel-default, kernel-default-base, kernel-default-devel, kernel-source), 4 product×package rows across 1 product lines (SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE): Known Not Affected 4. https://www.suse.com/security/cve/CVE-2026-53176/
ubuntu high CVE-2026-53176 high priority: Ubuntu including 162 source packages (linux, linux-allwinner-5.19, …), 1458 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): DNE 1051, ignored 172, needed 147, released 88. https://ubuntu.com/security/CVE-2026-53176

Affected software / configurations for CVE-2026-53176

Vendor Product Version Raw CPE
linux linux_kernel >= 3.10, < 5.10.259 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.11, < 5.15.210 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.16, < 6.1.176 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.2, < 6.6.143 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.94 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.18.36 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.19, < 7.0.13 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc6:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc7:*:*:*:*:*:*

References for CVE-2026-53176

URL Tags
https://git.kernel.org/stable/c/1ca40b243277c9e88be5e00bd3e083f71aefb93e Patch
https://git.kernel.org/stable/c/29e7b925ae6df64894e82ab6419994dc25580a8a Patch
https://git.kernel.org/stable/c/75ee6e4aa096aa9e7b2dd5c8ff98356e30aceefb Patch
https://git.kernel.org/stable/c/bd22740d7f14cb1c0289444cfd2c8d2938667c1d Patch
https://git.kernel.org/stable/c/c1234229399f4af12c553b1b0ffd978eeba65548 Patch
https://git.kernel.org/stable/c/c5584e089b5af7b3bf8bd5e8ca0560cbf32b0a47 Patch
https://git.kernel.org/stable/c/df422fd273c96c2ee5beb80fc21adc8c70c29260 Patch
https://git.kernel.org/stable/c/e8a013c0c3ca2f6708341a56612a3f6d6921620a Patch
https://access.redhat.com/security/cve/CVE-2026-53176 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2492741 Issue Tracking Third Party Advisory
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53176.json Third Party Advisory
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