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VulnerabilityAwaiting classification

CVE-2026-64046

CRITICAL · 9.8 CVSS v3.1 Published 2026-07-19
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 5 weeks old

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: tls: prevent chain-after-chain in plain text SG Sashiko points out that if end = 0 (start != 0) the current code will create a chain link to content type right after the wrap link: This would create a chain where the wrap link points directly to another chain link. The scatterlist API sg_next iterator does not recursively resolve consecutive chain links. meaning this is illegal input to crypto. The wrapping link is unnecessary if end = 0. end is the entry after the last one used so end = 0 means there's nothing pushed after the wrap: end start i v v v [ ]...[ ][ d ][ d ][ d ][ d ][rsv for wrap] Skip the wrapping in this case. TLS 1.3 can use the "wrapping slot" for it's chaining if end = 0. This avoids the chain-after-chain. Move the wrap chaining before marking END and chaining off content type, that feels like more logical ordering to me, but should not matter from functional perspective.

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

In the Linux kernel's TLS implementation, improper scatter-gather list handling in plain text SG processing allows a chain-after-chain scenario. When end=0 but start!=0, the code creates a chain link to content type directly after the wrap link, which the scatterlist API's sg_next iterator cannot recursively resolve. This produces illegal input to the crypto subsystem, potentially allowing kernel memory corruption or denial of service.

MitigationApply the Linux kernel patch that skips the wrapping when end=0 and allows TLS 1.3 to use the wrapping slot for chaining instead. Update to a kernel version containing this fix.

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

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. Identify kernel version
    Run `uname -r` or check `/proc/version` to get the running Linux kernel version
    Affected if The kernel version is older than the version containing the fix for this TLS scatter-gather list chaining issue
  2. Verify TLS kernel support is enabled
    Check if the kernel has TLS support compiled in or loaded: `cat /proc/cmdline | grep tls` or check for the `tls` kernel module with `lsmod | grep tls` or `modinfo tls`
    Affected if TLS kernel support (CONFIG_TLS or the tls module) is enabled and in use
  3. Confirm active TLS socket usage
    Inspect active network connections using TLS by running `ss -tlnp` or checking for processes using `AF_TLS` sockets via `cat /proc/net/tls`
    Affected if The system has active TLS connections using the kernel TLS implementation (entries appear in /proc/net/tls)
  4. Check scatter-gather list configuration
    This requires kernel debugging; inspect TLS connection scatter-gather lists via debugfs if available, or review kernel logs for crypto subsystem errors related to invalid SG chain handling
    Affected if Logs or debugging output show crypto errors indicating invalid 'chain-after-chain' SG list processing when end=0 and start!=0

A system is affected if it runs a Linux kernel older than the fixed version AND has the kernel TLS implementation (CONFIG_TLS or tls module) enabled with active TLS connections that could trigger the invalid scatter-gather list chaining condition.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Linux kernel patch that skips the wrapping when end=0 and allows TLS 1.3 to use the wrapping slot for chaining instead. Update to a kernel version containing this fix.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,560
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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-2026-64046 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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