tls: fix handling of zero-length records on the rx_list

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Summary

CVECVE-2025-39682
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-09-05 18:15:44 UTC
Updated2026-05-12 13:17:04 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from [email protected]

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

Problem Types: NVD-CWE-Other

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 84c61fe1a75b4255df1e1e7c054c9e6d048da417 2902c3ebcca52ca845c03182000e8d71d3a5196f git Not specified
CNA Linux Linux affected 84c61fe1a75b4255df1e1e7c054c9e6d048da417 c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677 git Not specified
CNA Linux Linux affected 84c61fe1a75b4255df1e1e7c054c9e6d048da417 3439c15ae91a517cf3c650ea15a8987699416ad9 git Not specified
CNA Linux Linux affected 84c61fe1a75b4255df1e1e7c054c9e6d048da417 29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e git Not specified
CNA Linux Linux affected 84c61fe1a75b4255df1e1e7c054c9e6d048da417 62708b9452f8eb77513115b17c4f8d1a22ebf843 git Not specified
CNA Linux Linux affected 6.0 Not specified
CNA Linux Linux unaffected 6.0 semver Not specified
CNA Linux Linux unaffected 6.1.149 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.103 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.44 6.12.* semver Not specified
CNA Linux Linux unaffected 6.16.4 6.16.* semver Not specified
CNA Linux Linux unaffected 6.17 * original_commit_for_fix Not specified
ADP Siemens SIMATIC CN 4100 affected V5.0 custom Not specified

References

ReferenceSourceLinkTags
lists.debian.org/debian-lts-announce/2025/10/msg00008.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Mailing List, Third Party Advisory
git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-032379.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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