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CVE-2025-39682

tls: fix handling of zero-length records on the rx_list

CVSS 3.1 Critical 9.8Known exploited (CISA KEV)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

Official description from the CVE record, published by Linux. Copyright © 1999-2026 The MITRE Corporation. See /security/cve/legal for the CVE license. View the record on cve.org

Key data

CVSS 3.1 Critical 9.8
Score published by Linux in the CVE record.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Network

    The vulnerable component can be reached over a network, possibly from the Internet.

  • Attack complexity: Low

    No special conditions are needed. The attack can be repeated at will.

  • Privileges required: None

    No account or privileges are needed.

  • User interaction: None

    No action from any user is needed.

  • Scope: Unchanged

    The impact stays within the vulnerable component.

  • Confidentiality impact: High

    Serious or total effect on the secrecy of data.

  • Integrity impact: High

    Serious or total effect on the trustworthiness of data.

  • Availability impact: High

    Serious or total effect on availability.

CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at first.org/cvss.

EPSS
Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.
Score
0.03312 (3.3% probability)
Percentile
88.7%
Scores of
Nov 10, 2026
Model
v2026.06.15
CISA Known Exploited Vulnerabilities
This CVE is listed in the CISA KEV catalog.
Name in the catalog
Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability
Added to the catalog
Sep 18, 2026
Federal due date
Sep 21, 2026
CISA assessment as of Sep 19, 2026
Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA.
Exploitation
Recorded by CISA as active
Automatable
yes
Technical impact
total
Weakness (CWE)
CWE catalog version 5.0.
CWE names: Copyright © 2006-2026, The MITRE Corporation. See /security/cve/legal for the CWE license.
  • CWE-754Improper Check for Unusual or Exceptional Conditions
Affected products
Products listed in the CVE record, as the CNA published them.

  • Linux

    • affected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 up to before 2902c3ebcca52ca845c03182000e8d71d3a5196f
    • affected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 up to before c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677
    • affected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 up to before 3439c15ae91a517cf3c650ea15a8987699416ad9
    • affected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 up to before 29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e
    • affected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 up to before 62708b9452f8eb77513115b17c4f8d1a22ebf843

  • Linux

    • affected: 6.0
    • unaffected: before 6.0
    • unaffected: 6.1.149 up to 6.1.*
    • unaffected: 6.6.103 up to 6.6.*
    • unaffected: 6.12.44 up to 6.12.*
    • unaffected: 6.16.4 up to 6.16.*
    • unaffected: 6.17 up to *
References
Links listed in the CVE record. They lead to other sites, which CubePath does not control.
Timeline
  1. ID reserved
  2. Record published
  3. Added to CISA KEV
  4. Record last updated

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Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 19:06 UTC. Sources and licenses