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CVE-2025-39682

9.8, critical Known exploited

Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab) CISA KEV catalogue (opens in a new tab)
CVSS
9.8, critical critical CVSS v3.1
EPSS, next 30 days
3% higher than 86.6% of scored CVEs
Exploitation
Confirmed in the wild
Published
5 Sept 2025a year ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 18 Sept 2026. US federal agencies had to remediate by 21 Sept 2026, a deadline that has passed.

Required action. 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.

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.

Details

Vendor
Linux and 1 more
Product
Linux
Weakness
CWE-754 (opens in a new tab)
Status
Analyzed
Updated
7 Oct 2026
Assigner
416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

References 8

Patches and fixes 5

Advisories 2

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Linux CVEs

Every Linux CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-53362 Linux Kernel Unspecified Vulnerability KEV EPSS 0.7% 7.8, high
  • CVE-2026-53266 Linux Kernel Out-of-Bounds Write Vulnerability KEV EPSS 0.8% 8.8, high
  • CVE-2026-31431 Linux Kernel Incorrect Resource Transfer Between Spheres Vulnerability KEV EPSS 3% 7.8, high
  • CVE-2025-39964 Linux Kernel Race Condition Vulnerability KEV EPSS 1% 5.5, medium
  • CVE-2025-38352 Linux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability KEV EPSS 1% 7.8, high
  • CVE-2024-53197 Linux Kernel Out-of-Bounds Access Vulnerability KEV EPSS 4% 7.8, high
  • CVE-2024-53150 Linux Kernel Out-of-Bounds Read Vulnerability KEV EPSS 1% 7.1, high
  • CVE-2024-53104 Linux Kernel Out-of-Bounds Write Vulnerability KEV EPSS 3% 7.8, high

Beyond this page

Is CVE-2025-39682 in your network?

This page tells you how dangerous CVE-2025-39682 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2025-39682 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

  • EXYS7600 OCELOT

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  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.