CVE-2025-39682tls: fix handling of zero-length records on the rx_list
Updated under an hour ago ()
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It affects Linux and 4 other products. Add what you run to find out whether that includes you.
CISA lists it as known exploited since Sep 18, 2026; federal agencies had to remediate by Sep 21, 2026. Treat that date as your deadline.
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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
- 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-754
- Known exploited
- Added to CISA KEV Sep 18, 2026; federal remediation due Sep 21, 2026Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
- EPSS (exploitation in the next 30 days)
- 2.88% (percentile 87)
- Assigned by
- Linux
- NVD analysis
- Analyzed
- Record last updated
- Oct 7, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 84c61fe1a75b4255df1e1e7c054c9e6d048da417 before 2902c3ebcca52ca845c03182000e8d71d3a5196f; from 84c61fe1a75b4255df1e1e7c054c9e6d048da417 before c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677; from 84c61fe1a75b4255df1e1e7c054c9e6d048da417 before 3439c15ae91a517cf3c650ea15a8987699416ad9; 84c61fe1a75b4255df1e1e7c054c9e6d048da417 builds before 29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e; from 84c61fe1a75b4255df1e1e7c054c9e6d048da417 before 62708b9452f8eb77513115b17c4f8d1a22ebf843 | CNA record |
Siemens SIMATIC CN 4100 siemens:simatic_cn_4100 (from the name) | before V5.0 | CISA ADP |
linux linux_kernel linux:linux_kernel | from 6.0 before 6.1.149; from 6.2 before 6.6.103; from 6.7 before 6.12.44; from 6.13 before 6.16.4; 6.17; 6.17 | NVD |
debian debian_linux debian:debian_linux | 11.0 | NVD |
siemens simatic_cn_4100_firmware siemens:simatic_cn_4100_firmware | before 5.0 | NVD |
References
- https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196fpatch
- https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677patch
- https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9patch
- https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42epatch
- https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843patch
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlmailing-list, third-party-advisory
- https://cert-portal.siemens.com/productcert/html/ssa-032379.htmlthird-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39682us-government-resource
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.