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Linux KernelOperating system · Linux

CVE-2025-39682

HIGH · 7.1 CVSS v3.1 Published 2025-09-05
Fix available
A fix is available. Upgrade to 6.1.149 / 6.6.103 or later.
See remediation →
73/100
Remediation priority · Elevated
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: tls: fix handling of zero-length records on the rx_list Each recvmsg() call must process either - only contiguous DATA records (any number of them) - one non-DATA record If the next record has different type than what has already been processed we break out of the main processing loop. If the record has already been decrypted (which may be the case for TLS 1.3 where we don't know type until decryption) we queue the pending record to the rx_list. Next recvmsg() will pick it up from there. Queuing the skb to rx_list after zero-copy decrypt is not possible, since in that case we decrypted directly to the user space buffer, and we don't have an skb to queue (darg.skb points to the ciphertext skb for access to metadata like length). Only data records are allowed zero-copy, and we break the processing loop after each non-data record. So we should never zero-copy and then find out that the record type has changed. The corner case we missed is when the initial record comes from rx_list, and it's zero length.

In the news

Third-party coverage
Trending covered by 1 outlet this week · latest 11mo ago

Surfaced from public web coverage — external links open in a new tab.

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

A detailed technical summary for this CVE is being prepared.

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:>= 6.0, < 6.1.149>= 6.2, < 6.6.103>= 6.7, < 6.12.44>= 6.13, < 6.16.4= 6.17
Debian LinuxOperating system
Affected:= 11.0

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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

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

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 6.1.149 / 6.6.103 / 6.12.44 or later
Fixed in 6.1.1496.6.1036.12.44
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to Linux kernel 6.1.149+, 6.6.103+, 6.12.44+, or 6.16.4+ (or Debian vendor patch when available)

  1. Determine current kernel version with 'uname -r' and identify if it's affected by checking against the vulnerable ranges: >= 6.0 and < 6.1.149, >= 6.2 and < 6.6.103, >= 6.7 and < 6.12.44, or >= 6.13 and < 6.16.4
  2. Schedule a maintenance window as kernel upgrades require system reboot
  3. For Debian 11 systems, check if Debian Security Advisory (DSA) has been issued for this CVE and apply vendor patch if available via 'apt-get update && apt-get install linux-image-$(uname -r)'
  4. If upstream kernel upgrade is preferred, upgrade to a fixed release: 6.1.149 or later, 6.6.103 or later, 6.12.44 or later, or 6.16.4 or later
  5. After upgrade, reboot the system and verify the new kernel version is running with 'uname -r'
  6. Confirm the fix is present by checking the kernel config includes TLS support or reviewing the specific commit 2902c3ebcca5 in the kernel source
Caveat Kernel upgrades require system downtime for reboot; verify hardware/driver compatibility with new kernel before production deployment

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

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get the upgrade done

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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-2025-39682 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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