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.

zetlyn/cve-nvd vulnerability cve CVE-2025-39682 cpe cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:* cpe cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:* cpe cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* cpe cpe:2.3:o:siemens:simatic_cn_4100_firmware:*:*:*:*:*:*:*:* cpe cpe:2.3:h:siemens:simatic_cn_4100:-:*:*:*:*:*:*:* known 2025-09-05

https://nvd.nist.gov/vuln/detail/CVE-2025-39682

Properties

cvss9.8
receipt
Source
NVD
Its words
9.8
Read by
field:cve.metrics.cvssMetricV31[].cvssData.baseScore
Said since
2026-09-29 09:45 UTC
Last answered
2026-10-05 12:24 UTC
Original
open at the source
What the source handed over
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productLinux
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Source
NVD
Its words
Linux
Read by
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Said since
2026-09-29 17:49 UTC
Last answered
2026-10-05 12:24 UTC
Original
open at the source
2026-09-29 17:49 UTCLinux
2026-09-29 09:45 UTC—
What the source handed over
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      }
    ],
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  }
}
statusAnalyzed
receipt
Source
NVD
Its words
Analyzed
Read by
field:cve.vulnStatus
Said since
2026-09-29 09:45 UTC
Last answered
2026-10-05 12:24 UTC
Original
open at the source
What the source handed over
{
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                "status": "unaffected",
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                "status": "affected",
                "version": "0",
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            ]
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        "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
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    "cisaActionDue": "2026-09-21",
    "cisaExploitAdd": "2026-09-18",
    "cisaRequiredAction": "Apply 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.",
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                "vulnerable": true
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    "cveTags": [],
    "descriptions": [
      {
        "lang": "en",
        "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntls: fix handling of zero-length records on the rx_list\n\nEach recvmsg() call must process either\n - only contiguous DATA records (any number of them)\n - one non-DATA record\n\nIf the next record has different type than what has already been\nprocessed we break out of the main processing loop. If the record\nhas already been decrypted (which may be the case for TLS 1.3 where\nwe don't know type until decryption) we queue the pending record\nto the rx_list. Next recvmsg() will pick it up from there.\n\nQueuing the skb to rx_list after zero-copy decrypt is not possible,\nsince in that case we decrypted directly to the user space buffer,\nand we don't have an skb to queue (darg.skb points to the ciphertext\nskb for access to metadata like length).\n\nOnly data records are allowed zero-copy, and we break the processing\nloop after each non-data record. So we should never zero-copy and\nthen find out that the record type has changed. The corner case\nwe missed is when the initial record comes from rx_list, and it's\nzero length."
      }
    ],
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    "lastModified": "2026-09-21T12:00:36.613",
    "metrics": {
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  }
}
vendorLinux
receipt
Source
NVD
Its words
Linux
Read by
field:cve.affected[].affectedData[].vendor
Said since
2026-09-29 17:49 UTC
Last answered
2026-10-05 12:24 UTC
Original
open at the source
2026-09-29 17:49 UTCLinux
2026-09-29 09:45 UTC—
What the source handed over
{
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            "programFiles": [
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              },
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            ]
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            ],
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Text

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.