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Linux KernelOperating system · Linux

CVE-2026-43341

CRITICAL · 9.8 CVSS v3.1 Published 2026-05-08
Fix available
A fix is available. Upgrade to 6.1.168 / 6.6.134 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: net/ipv6: ioam6: prevent schema length wraparound in trace fill ioam6_fill_trace_data() stores the schema contribution to the trace length in a u8. With bit 22 enabled and the largest schema payload, sclen becomes 1 + 1020 / 4, wraps from 256 to 0, and bypasses the remaining-space check. __ioam6_fill_trace_data() then positions the write cursor without reserving the schema area but still copies the 4-byte schema header and the full schema payload, overrunning the trace buffer. Keep sclen in an unsigned int so the remaining-space check and the write cursor calculation both see the full schema length.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A buffer overflow vulnerability in the Linux kernel's IPv6 IOAM (Input/Output Accounting Manager) trace functionality occurs when the schema length (sclen) is stored in a u8 (8-bit unsigned integer). With bit 22 enabled and the maximum schema payload (1020 bytes), sclen calculates as 1 + 1020/4 = 256, which wraps around to 0 due to the 8-bit limit, bypassing the remaining-space check and causing __ioam6_fill_trace_data() to position the write cursor without reserving schema space, resulting in a trace buffer overrun.

MitigationApply the kernel patch that changes sclen from u8 to unsigned int to prevent the wraparound, or update to a kernel version containing this fix. This is a kernel-level vulnerability requiring a system update and reboot.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 5.15, < 6.1.168>= 6.2, < 6.6.134>= 6.7, < 6.12.81>= 6.13, < 6.18.22>= 6.19, < 6.19.12= 7.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check the running kernel version
    Run `uname -r` or `cat /proc/version` to obtain the kernel version, then compare it against the affected ranges: >= 5.15 and < 6.1.168; >= 6.2 and < 6.6.134; >= 6.7 and < 6.12.81; >= 6.13 and < 6.18.22; >= 6.19 and < 6.19.12; = 7.0
    Affected if The kernel version falls within any of the listed affected ranges and is not a patched version
  2. Determine if IPv6 IOAM is enabled
    Check IOAM6 sysctl settings with `sysctl -a | grep -i ioam6` or inspect `/proc/sys/net/ipv6/conf/*/ioam6_enabled` for each network interface
    Affected if IOAM6 is enabled (value is 1 or non-zero) on any network interface or system-wide setting
  3. Verify if IOAM6 kernel module is loaded
    Run `lsmod | grep ioam6` to list loaded modules, or check `/sys/module/ioam6*` directory existence
    Affected if The ioam6 or ioam6_*/kernel module is loaded into memory
  4. Check for IOAM6 proc filesystem entries
    Inspect `/proc/net/ioam6` or `/proc/net/ioam6_trace` entries if they exist: `ls -la /proc/net/ | grep ioam6`
    Affected if IOAM6 trace proc entries are present and the trace functionality is actively in use

The system is affected only if it runs a vulnerable kernel version AND has IPv6 IOAM trace functionality enabled or loaded as a module.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.1.168 / 6.6.134 / 6.12.81 or later
Fixed in 6.1.1686.6.1346.12.81
Vendor patch git.kernel.org →
Interim mitigation

Apply the kernel patch that changes sclen from u8 to unsigned int to prevent the wraparound, or update to a kernel version containing this fix. This is a kernel-level vulnerability requiring a system update and reboot.

Recommended fix High confidence

Upgrade to kernel 6.1.168+ (for 5.15.x), 6.6.134+ (for 6.2-6.5.x), 6.12.81+ (for 6.7-6.11.x), or 6.18.22+ (for 6.13-6.17.x)

  1. Identify the currently running kernel version using `uname -r`
  2. Determine which version range your current kernel falls into based on the affected versions: >= 5.15 < 6.1.168, >= 6.2 < 6.6.134, >= 6.7 < 6.12.81, or >= 6.13 < 6.18.22
  3. If running 5.15.x: upgrade to kernel version 6.1.168 or later
  4. If running 6.2.x through 6.5.x: upgrade to kernel version 6.6.134 or later
  5. If running 6.7.x through 6.11.x: upgrade to kernel version 6.12.81 or later
  6. If running 6.13.x through 6.17.x: upgrade to kernel version 6.18.22 or later
  7. Alternatively, apply the upstream fix commit 184d2e9db27c0f76226b5cad16fe29510a5d2280 which changes the schema length variable from 'u8 sclen' to 'unsigned int sclen' to prevent integer wraparound
  8. After upgrade, verify the fix is applied by checking the ioam6 code in net/ipv6/ioam6.c for the unsigned int sclen declaration
Caveat Kernel upgrades may require reboot and could introduce compatibility issues with custom modules or specific hardware drivers; ensure backup and test in staging if possible

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing6.0 h
  • Review / QA4.0 h
16.0 hours of engineering $2,780
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-43341 in production — separate from our analysis above.

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What this is

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  • Version or environment caveats, and links to real fixes
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