# CVE-2025-39682

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.

- Page: https://www.vulneraibility.com/cve/CVE-2025-39682
- CVSS: 9.8
- Known exploited: yes, in CISA KEV since 2026-09-18; CISA due date 2026-09-21
- EPSS: 3.25%
- Unvetted proof-of-concept code on GitHub: 2 GitHub proofs of concept (first 2025-10-14)
- CISA SSVC: exploitation active, automatable yes, technical impact total (assessed 2026-09-19)
- Weakness: CWE-754
- Published: 2025-09-05

## Affected versions

- Linux: affected >= 84c61fe1a75b4255df1e1e7c054c9e6d048da417 and < 2902c3ebcca52ca845c03182000e8d71d3a5196f; >= 84c61fe1a75b4255df1e1e7c054c9e6d048da417 and < c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677; >= 84c61fe1a75b4255df1e1e7c054c9e6d048da417 and < 3439c15ae91a517cf3c650ea15a8987699416ad9; >= 84c61fe1a75b4255df1e1e7c054c9e6d048da417 and < 29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e; >= 84c61fe1a75b4255df1e1e7c054c9e6d048da417 and < 62708b9452f8eb77513115b17c4f8d1a22ebf843; 6.0; fixed in < 6.0, >= 6.1.149 and <= 6.1.*, >= 6.6.103 and <= 6.6.*, >= 6.12.44 and <= 6.12.*, >= 6.16.4 and <= 6.16.*, >= 6.17 and <= *

A version outside these ranges is not a statement that it is unaffected.

## References

- [other] https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f
- [other] https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677
- [other] https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9
- [other] https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e
- [other] https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843
- [other] https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
- [other] https://cert-portal.siemens.com/productcert/html/ssa-032379.html
- [other] https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39682

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Summary, impact and action are written by the vulneraibility.com AI analysis pipeline from the CVE record, NVD, CISA and FIRST data; verify against the references.