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Linux Kernel CVE-2026-80637

| EUVDEUVD-2026-67513 HIGH
2026-08-28 Linux GHSA-h35g-h9xw-jfv9
Denial Of Service Linux Red Hat Suse
7.5
CVSS 3.1 · Vendor: Linux
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Severity by source

Vendor (Linux) PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
5.9 MEDIUM

AC:H assigned because exploitation requires both a strict-alignment CPU architecture and synproxy explicitly configured by an administrator in netfilter rules.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
HIGH
qualitative
Red Hat
5.5 MEDIUM
qualitative

Primary rating from Vendor (Linux).

CVSS VectorVendor: Linux

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

5
Analysis Generated
Aug 29, 2026 - 07:42 vuln.today
CVSS changed
Aug 29, 2026 - 07:22 NVD
7.5 (HIGH)
Patch available
Aug 28, 2026 - 09:02 EUVD
CVE Published
Aug 28, 2026 - 06:48 cve.org
HIGH 7.5
CVE Published
Aug 28, 2026 - 06:48 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

In the Linux kernel, the following vulnerability has been resolved:

netfilter: synproxy: fix unaligned memory access in timestamp adjustment

Use get_unaligned_be32() and put_unaligned_be32() to safely read and write the timestamp fields. This prevents performance degradation due to unaligned memory access or even a crash on strict alignment architectures.

This follows the implementation of timestamp parsing in the networking stack at tcp_parse_options() and synproxy_parse_options().

AnalysisAI

Unaligned memory access in the Linux kernel netfilter synproxy timestamp adjustment code can crash the kernel or degrade performance on strict-alignment CPU architectures when synproxy is actively configured. Systems running synproxy as a SYN-flood mitigation layer on architectures such as SPARC, classic MIPS, or ARM without hardware unaligned-access emulation are exposed to remote-triggered denial of service via crafted TCP packets. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

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Vulnerability AssessmentAI

Exploitation Two simultaneous prerequisites must be met for successful exploitation: (1) The Linux kernel netfilter synproxy module must be actively deployed in iptables or nftables rules - this is a non-default configuration requiring root/administrator privileges to establish, meaning the administrator must have intentionally enabled synproxy-based SYN-flood mitigation; AND (2) The host hardware must enforce strict memory alignment - architectures at risk include SPARC, classic MIPS, and ARM configurations without hardware transparent unaligned-access emulation. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The NVD-assigned CVSS 3.1 vector AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (7.5 High) represents the ceiling of impact but overstates realistic risk in two important ways. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Upgrade to Linux kernel 6.12.97, 6.18.40, 7.1.5, or 7.2 depending on the active stable branch; the four upstream fix commits are available at git.kernel.org (2b8e7aaa38002d8ee2f48d87b1f392eadd8e98c4, 5c9c67cf7a3d16051dfb90e98836f530964dfb8e, ea3d2caa5bfacf5db5c1cad521ca5d9144edd9a7, 992c20bc8a4aba220c8b95b467d049289778dad6). … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Immediately identify all production Linux systems running synproxy on SPARC, classic MIPS, or ARM architectures. …

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 16.0 Affected

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CVE-2026-80637 vulnerability details – vuln.today
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