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Linux Kernel EUVDEUVD-2026-55612

| CVE-2026-68426 CRITICAL
Use After Free (CWE-416)
2026-08-10 Linux GHSA-g9mw-m3g9-8x3m
Information Disclosure Linux Use After Free Memory Corruption
9.8
CVSS 3.1 · Vendor: Linux
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Send heavy GSO traffic through IPsec tunnel
  2. Delivery
    Async crypto engine steals last GSO segment (-EINPROGRESS)
  3. Exploit
    Head ->prev left pointing at freed segment
  4. Execution
    validate_xmit_skb_list writes tail->next through stale pointer
  5. Impact
    Kernel use-after-free / panic (DoS)

Vulnerability Assessment

Weakness
CWE
CWE-416
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Exploitation Conditions

Requires the target host to be configured for IPsec via the kernel xfrm framework AND to use asynchronous crypto offload (a hardware crypto accelerator or async crypto driver whose ->xmit() can return -EINPROGRESS), AND to be transmitting GSO (segmentation-offload) traffic through that path. The race only fires when the specific segment stolen by the crypto engine is the last segment of the GSO list, making the timing window narrow. Limiting factors: hosts without IPsec, or IPsec configured with synchronous software crypto, are not exposed; the condition is non-default for general-purpose servers and is most relevant to VPN gateways, IPsec routers, and crypto-accelerated appliances. Despite the AV:N/PR:N CVSS metrics, exploitation is a timing-dependent kernel race rather than a straightforward remote request.
Impact

The published CVSS of 9.8 (AV:N/AC:L/PR:N/UI:N, C:H/I:H/A:H) overstates real-world risk and appears to be an automated worst-case rating typical of bulk kernel CVEs. Countervailing signals dominate: EPSS is only 0.16% (6th percentile), there is no KEV listing and no known POC, and the vulnerability is a timing-dependent race that only manifests when the host is configured for IPsec (xfrm) with asynchronous crypto offload and is handling GSO traffic - a meaningful but far-from-default deployment mode. The description implies denial of service / kernel memory corruption rather than a demonstrated path to remote code execution, so the C:H/I:H mapping is optimistic; a realistic outcome is a kernel panic or memory-safety fault. Because the trigger is a race across the crypto-completion boundary, the AC:L (low complexity) metric is questionable and AC:H is more defensible. Net assessment: a legitimate memory-safety bug worth patching in the normal cycle on IPsec gateways and VPN concentrators, but not a drop-everything emergency for the general fleet; organizations not running IPsec with async crypto offload are effectively unaffected.
Exploit ScenarioDerived

On an IPsec VPN gateway using an async crypto engine, an attacker (or ordinary heavy traffic) drives large GSO flows through the tunnel so that the final segment of a GSO list is stolen by the crypto engine at just the wrong moment; the stale tail pointer then causes the kernel to write into freed memory, panicking the gateway and dropping all tunnels. Reliably weaponizing the resulting use-after-free for code execution would be significantly harder and no public POC is known.
Act Now Prioritize within 24-48h. Why: CRITICAL severity.
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 14, 2026

Use-after-free in the Linux kernel's IPsec transmit path (xfrm) occurs when validate_xmit_xfrm() processes a GSO segment list and async crypto offload steals the final segment via -EINPROGRESS, leaving the list head's ->prev pointing at a segment now owned (and potentially freed) by the crypto engine. validate_xmit_skb_list() then writes through that stale tail pointer, corrupting freed memory; the practical impact is kernel memory corruption and likely crash on systems using IPsec with asynchronous crypto. No public exploit identified at time of analysis, EPSS is low (0.16%), and it is not listed in CISA KEV, so this is a patch-and-move-on issue rather than an active-exploitation emergency.

RemediationAI

Patch available per vendor: upgrade to a fixed stable kernel - 6.18.42 or later in that series, or 7.1.6 / 7.2-rc4 and later - which carry commits bbca7cc3b2b4b10afbfee99b81d9ee78f5423046, 3f4c3919baf0944ad96580467c302bc6c7758b00, or 33e1b0d25ca0d2818c635ff80e6aa0d295e08a98 (https://git.kernel.org/stable/c/33e1b0d25ca0d2818c635ff80e6aa0d295e08a98). Distribution users should apply their vendor's next kernel update rather than back-porting by hand. As an interim compensating control on hosts where you cannot reboot immediately, disabling asynchronous/offloaded IPsec crypto (forcing synchronous software crypto for xfrm) avoids the -EINPROGRESS path that triggers the race, at the cost of reduced IPsec throughput and higher CPU load; alternatively, on systems that do not require IPsec, ensuring xfrm/IPsec is not in use removes exposure entirely. There is no need for network-level blocking since the condition is internal to the egress crypto path.

Affected VersionsENISA

Linux f53c723902d1ac5f0b0a11d7c9dcbff748dde74e <bbca7cc3b2b4b10afbfee99b81d9ee78f5423046
Linux f53c723902d1ac5f0b0a11d7c9dcbff748dde74e <3f4c3919baf0944ad96580467c302bc6c7758b00
Linux f53c723902d1ac5f0b0a11d7c9dcbff748dde74e <33e1b0d25ca0d2818c635ff80e6aa0d295e08a98
Linux patch: 7.1.6
Linux patch: 7.2-rc4
Linux 4.16
Linux patch: 6.18.42
Linux patch: 0

Affected Packages

euvd linux no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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Technical ContextAI · show details

The bug lives in the kernel networking stack's xfrm (IP transformation / IPsec) egress path. skb_gso_segment() splits a large GSO super-packet into a linked list of segment skbs and, by convention, sets the list head's skb->prev to the last segment - an invariant that validate_xmit_skb_list() depends on to compute its tail (tail = skb->prev). When IPsec is offloaded to an asynchronous crypto engine, a per-segment ->xmit() can return -EINPROGRESS, meaning that segment is unlinked and handed to the crypto hardware/driver. validate_xmit_xfrm() failed to repoint the head's ->prev after removing the last segment, so a subsequent tail->next = skb dereferences memory that may already be freed. This is a classic use-after-free (CWE-416) arising from a broken list invariant, and the CPE data scopes it to cpe:2.3:a:linux:linux, i.e. the mainline kernel. The fix simply repoints skb->prev to the last retained segment before returning.

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Severity by source

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 7.0 HIGH

Triggered by network traffic but only under a narrow crypto-completion race requiring IPsec async offload, so AC:H; impact is primarily kernel crash (A:H) with uncertain, limited C/I.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
4.0 AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N
SUSE 7.0 HIGH
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Red Hat 7.3 HIGH

Primary rating from Vendor (Linux).

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

4
CVSS changed
Aug 13, 2026 - 23:37 NVD
9.8 (CRITICAL)
Patch available
Aug 10, 2026 - 14:18 EUVD
CVE Published
Aug 10, 2026 - 12:04 cve.org
UNKNOWN (no severity yet)
CVE Published
Aug 10, 2026 - 12:04 cve.org
CRITICAL 9.8

DescriptionCVE.org

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

xfrm: fix stale skb->prev after async crypto steals a GSO segment

skb_gso_segment() leaves the segment list head with ->prev pointing at the last segment, an invariant validate_xmit_skb_list() relies on when it sets its tail pointer (tail = skb->prev).

When validate_xmit_xfrm() walks a GSO list and some segments are stolen by async crypto (->xmit() returns -EINPROGRESS), those segments are unlinked from the list but the head ->prev is never updated. If the last segment is the one stolen, the returned head still has ->prev pointing at it, even though it is now owned by the crypto engine and may be freed. validate_xmit_skb_list() later does tail->next = skb, writing through that stale pointer -- a use-after-free.

Repoint skb->prev at the last retained segment before returning.

Executive ViewAI

Why It Matters

Linux kernel IPsec systems could experience unexpected crashes due to a memory corruption vulnerability, affecting network security infrastructure and VPN gateways relying on hardware-accelerated encryption. The threat is contained: no public exploit identified at time of analysis, patch is immediately available, and impact is limited to specific configurations using asynchronous crypto offload. Organizations should prioritize patching critical network infrastructure within the next week.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.2%
Top 94% exploitable
Prevalence
Ubiquitous
Linux kernel runs on a vast fraction of servers and appliances worldwide
Data Quality
6 sources
Confidence: High
EUVD NVD CVE.org EPSS MSRC Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
High

Priority Score

49
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Use After Free HIGH

Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.

Memory Corruption HIGH

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Same weakness CWE-416 – Use After Free

View all
CVE-2019-0708 CRITICAL POC
9.8
CVE-2015-5119 CRITICAL POC
9.8
CVE-2014-0322 HIGH POC
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CVE-2012-4792 HIGH POC
8.8
CVE-2009-4324 HIGH POC
7.8
CVE-2015-0313 CRITICAL POC
9.8
CVE-2015-5122 CRITICAL POC
9.8
CVE-2013-2551 HIGH POC
8.8

Same technique Information Disclosure

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CVE-2019-2725 CRITICAL POC
9.8
CVE-2021-34523 CRITICAL POC
9.0
CVE-2013-2251 CRITICAL POC
9.8
CVE-2017-5638 CRITICAL POC
9.8
CVE-2025-24813 CRITICAL POC
9.8
CVE-2025-68613 HIGH POC
8.8
CVE-2015-1701 HIGH POC
7.8
CVE-2017-0147 HIGH POC
7.5

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

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-68426 ADVISORY https://ubuntu.com/security/notices/USN-8781-1 ADVISORY https://vuldb.com/vuln/387657 REF https://git.kernel.org/stable/c/33e1b0d25ca0d2818c635ff80e6aa0d295e08a98 REF https://git.kernel.org/stable/c/3f4c3919baf0944ad96580467c302bc6c7758b00 REF https://git.kernel.org/stable/c/4927ab8a8acc8db4fad33e803d1d35e0b16cef83 REF https://git.kernel.org/stable/c/4e695742396be18d5291c310a3d7c450959d647a REF https://git.kernel.org/stable/c/b58731e0570bfd3989999fc2baf9ee4fecd5bec6 REF https://git.kernel.org/stable/c/bbca7cc3b2b4b10afbfee99b81d9ee78f5423046

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