Answer in brief
CVE-2025-39682 records a Critical severity (CVSS 9.8) vulnerability in tls: fix handling of zero-length records on the rx_list. The current sources mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC CN 4100 (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.8. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC CN 4100 (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:h:siemens:simatic_cn_4100:-:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:siemens:simatic_cn_4100_firmware:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=84c61fe1a75b4255df1e1e7c054c9e6d048da417 <2902c3ebcca52ca845c03182000e8d71d3a5196f || >=84c61fe1a75b4255df1e1e7c054c9e6d048da417 <c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677 || >=84c61fe1a75b4255df1e1e7c054c9e6d048da417 <3439c15ae91a517cf3c650ea15a8987699416ad9 || >=84c61fe1a75b4255df1e1e7c054c9e6d048da417 <29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e || >=84c61fe1a75b4255df1e1e7c054c9e6d048da417 <62708b9452f8eb77513115b17c4f8d1a22ebf843 | 2902c3ebcca52ca845c03182000e8d71d3a5196f, c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677, 3439c15ae91a517cf3c650ea15a8987699416ad9, 29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e, 62708b9452f8eb77513115b17c4f8d1a22ebf843 |
| Linux/Linuxgeneric | 6.0 | Not reported |
| Siemens/SIMATIC CN 4100generic | >=0 <V5.0 | V5.0 |
Published upstream
Sep 5, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
Added to CISA KEV
Sep 18, 2026
Evidence: source:kev:kev:kev:recordIn 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.
Quoted source text, attributed separately from HOL analysis.