CVE-2025-39682
linux · published 2025-09-05
Source record Collected from the National Vulnerability Database (NVD)
CISA Known Exploited Vulnerabilities
CISA lists this CVE as known exploited (added 2026-09-18).
- CISA's name for it: Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability
- CISA's description: Linux Kernel contains an improper check for unusual or exceptional conditions vulnerability in the TLS receive path which allows a zero-length record retrieved from the rx_list to bypass the intended recvmsg() record-type handling, potentially causing subsequent TLS records to be processed using incorrect zero-copy and queuing assumptions. The impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version.
- Known ransomware campaign use, per CISA: Unknown
Source: CISA KEV catalog (CC0 1.0).
Description
Description by kernel.org via the CVE Program.
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.
Filed by kernel.org; not a statement by linux.
Status at the source
- NVD status: Analyzed
Affected products, as the source lists them
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux | 84c61fe1a75b4255df1e1e7c054c9e6d048da417 – before 2902c3ebcca52ca845c03182000e8d71d3a5196f: affected 84c61fe1a75b4255df1e1e7c054c9e6d048da417 – before c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677: affected 84c61fe1a75b4255df1e1e7c054c9e6d048da417 – before 3439c15ae91a517cf3c650ea15a8987699416ad9: affected 84c61fe1a75b4255df1e1e7c054c9e6d048da417 – before 29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e: affected 84c61fe1a75b4255df1e1e7c054c9e6d048da417 – before 62708b9452f8eb77513115b17c4f8d1a22ebf843: affected |
| Linux | Linux | 6.0: affected 0 – before 6.0: unaffected 6.1.149 – 6.1.* and earlier: unaffected 6.6.103 – 6.6.* and earlier: unaffected 6.12.44 – 6.12.* and earlier: unaffected 6.16.4 – 6.16.* and earlier: unaffected 6.17 – * and earlier: unaffected |
Added by siemens-SADP (Authorized Data Publisher)
| Vendor | Product | Versions |
|---|---|---|
| Siemens | SIMATIC CN 4100 | 0 – before V5.0: affected |
Products named in NVD's CPE match criteria (3)
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*cpe:2.3:o:siemens:simatic_cn_4100_firmware:*:*:*:*:*:*:*:*
DeSpy has not checked any unit, hardware revision or firmware. A product missing here is not a statement that it is unaffected.
Scores, as their sources published them
- CVSS 3.1: 9.8 CRITICAL — as published by kernel.org (Secondary)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 3.1: 9.8 CRITICAL — as published by NIST (Primary)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - SSVC — CISA's assessment (SSVC 2.0.3, CISA Coordinator): Exploitation: active · Automatable: yes · Technical impact: total
DeSpy does not score records. These are the sources' own values.
Weaknesses
NVD-CWE-Other, CWE-754
Sources
References the source lists
- https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f
- https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e
- https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9
- https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843
- https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39682
Source dates: published 2025-09-05, last changed 2026-10-07. DeSpy's copy of this version is dated 2026-10-07.
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