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Linux Kernel CVE-2026-72351

| EUVDEUVD-2026-59250 CRITICAL
2026-08-15 Linux GHSA-pcv5-gx25-24wj
Information Disclosure Linux Red Hat Suse
Critical
Disputed · 9.8 Vendor: Linux
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Severity by source

Sources disagree (Medium–Critical)
Vendor (Linux) PRIMARY
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
4.8 MEDIUM

Remote unauthenticated malformed packet (AV:N/PR:N/UI:N), but AC:H because it needs a non-default GUE remote-checksum tunnel; impact is a small out-of-bounds read (C:L) with possible instability (A:L), not RCE.

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

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor: Linux

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

Lifecycle Timeline

5
Analysis Generated
Aug 17, 2026 - 08:41 vuln.today
CVSS changed
Aug 17, 2026 - 06:22 NVD
9.8 (CRITICAL)
Patch available
Aug 15, 2026 - 07:20 EUVD
CVE Published
Aug 15, 2026 - 05:55 cve.org
UNKNOWN (no severity yet)
CVE Published
Aug 15, 2026 - 05:55 cve.org
CRITICAL 9.8

DescriptionCVE.org

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

gue: validate REMCSUM private option length

GUE private flags can indicate that remote checksum offload metadata is present. The private flags field itself is accounted for by guehdr_flags_len(), but guehdr_priv_flags_len() currently returns 0 even when GUE_PFLAG_REMCSUM is set.

This lets a packet with only the private flags field pass validate_gue_flags(), after which gue_remcsum() and gue_gro_remcsum() read the missing REMCSUM start/offset fields from the following bytes.

Account for GUE_PLEN_REMCSUM when GUE_PFLAG_REMCSUM is present so that malformed packets are rejected during option validation.

AnalysisAI

Out-of-bounds read in the Linux kernel's Generic UDP Encapsulation (GUE) tunnel receive path lets remote attackers read adjacent packet memory by sending malformed GUE packets that set the GUE_PFLAG_REMCSUM private flag without carrying the corresponding remote-checksum start/offset bytes. Because guehdr_priv_flags_len() failed to account for GUE_PLEN_REMCSUM, such truncated packets slipped past validate_gue_flags() and were then processed by gue_remcsum()/gue_gro_remcsum(), which read the missing fields from following bytes. There is no public exploit identified at time of analysis; EPSS is low (0.22%, 13th percentile) and the flaw is not in CISA KEV, so despite the headline CVSS 9.8 the realistic impact is information disclosure/instability rather than confirmed remote code execution.

Technical ContextAI

GUE (Generic UDP Encapsulation, foo-over-UDP) is a Linux tunneling mechanism that wraps encapsulated traffic in a UDP header plus a GUE header carrying flags and optional metadata. GUE supports 'private' flags, one of which (GUE_PFLAG_REMCSUM) signals that Remote Checksum Offload metadata - a start and offset pair - accompanies the header. Option length must be computed before those fields are dereferenced: guehdr_flags_len() sizes the standard flags while guehdr_priv_flags_len() sizes the private-flag options. The bug is a length-validation error of this class (functionally CWE-125 Out-of-Bounds Read / improper length handling; NVD lists CWE as N/A): guehdr_priv_flags_len() returned 0 for GUE_PFLAG_REMCSUM, so validate_gue_flags() did not require the REMCSUM start/offset bytes to be present, and the subsequent gue_remcsum()/gue_gro_remcsum() paths read those fields out of bounds. Per the CPE data the affected product is the Linux kernel (cpe:2.3:a:linux:linux:*), specifically the net/ipv4 fou/gue foo-over-UDP encapsulation code.

RemediationAI

Vendor-released patch: upgrade to a fixed stable kernel for your branch - 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40, or 7.1.5 (mainline fix ~7.2-rc3) - using the stable commits at git.kernel.org (e.g. https://git.kernel.org/stable/c/158b9995d3c87f3b93f5c22df54a12e12a3438b3) and rebuild/redeploy or take your distribution's patched kernel package. As a compensating control on hosts that cannot immediately reboot into a new kernel, avoid or tear down GUE/foo-over-UDP tunnel endpoints (e.g. remove the ip fou/GUE decapsulation configuration) so the vulnerable receive path is not reachable - the trade-off is loss of any GUE-based encapsulation in use. Where GUE must remain enabled, restrict which peers can reach the GUE UDP port with firewall rules so only trusted tunnel endpoints can send decapsulated traffic, accepting that this narrows but does not eliminate exposure. Because the fix ships as a source patch across many stable commits rather than a single tagged product release, confirm your distribution kernel actually includes the referenced commit before considering systems remediated.

Same technique Information Disclosure

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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-2026-72351 vulnerability details – vuln.today
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