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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.51%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 7.1 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- EPSS
- 0.51% probability · 42th percentile
- CISA KEV
- Not listed
- Affected
- linux/linux kernel · debian/debian linux
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196fPatch
- https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42ePatch
- https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9Patch
- https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843Patch
- https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677Patch
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlMailing List, Third Party Advisory
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.