CVE-2025-39682
CriticalExploitedPublic exploitLinux kernel: tls: fix handling of zero-length records on the rx_list
Published Sep 5, 2025 · Updated Oct 15, 2026 · Also known as A-440544511, ASB-A-440544511, DEBIAN-CVE-2025-39682, ROOT-OS-DEBIAN-12-CVE-2025-39682, ROOT-OS-DEBIAN-13-CVE-2025-39682, ROOT-OS-UBUNTU-2404-CVE-2025-39682, UBUNTU-CVE-2025-39682
Key Facts
Patch immediately- CVE-2025-39682 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting linux-aws-6.12 (chainguard), linux-aws-6.18 (chainguard), linux-azure-6.12 (chainguard) and 22 more products.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Sep 18, 2026. Public exploit code is available.
- EPSS estimates a 2.9% probability of exploitation in the next 30 days.
- Fixed versions are available, including :linux_kernel: :2026-03-05, bpftool 1:6.1.150-174.273.amzn2023, bpftool 6.1.153-1.ph5.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
2.9%
Higher than 86.6% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2025-39682 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Sep 18, 2026 | Sep 21, 2026 | Not reported |
| Industry KEV feed | Sep 18, 2026 | Sep 21, 2026 | Not reported |
| CIRCL KEV | Sep 18, 2026 | Sep 21, 2026 | Not reported |
| ENISA EUVD | Sep 18, 2026 | n/a | Not reported |
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.
Affected Products
2,506 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| linux-aws-6.12chainguard | See advisory | 6.12.76-r0 |
| linux-aws-6.18chainguard | See advisory | 6.18.17-r0 |
| linux-azure-6.12chainguard | See advisory | 6.12.76-r0 |
| linux-azure-6.18chainguard | See advisory | 6.18.17-r0 |
| linux-desktop-6.18chainguard | See advisory | 6.18.48-r0 |
Patched Releases
:linux_kernel:
:2026-03-05
bpftool
1:6.1.150-174.273.amzn2023, 6.1.153-1.ph5, 7.6.0+6.14.0-34.34
bpftool6.12
1:6.12.46-66.121.amzn2023
cluster-md-kmp-64kb
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
cluster-md-kmp-azure
6.4.0-150600.8.52.1
cluster-md-kmp-default
6.12.0-160000.6.1, 6.4.0-150600.23.73.1, 6.4.0-150700.53.19.1
cluster-md-kmp-rt
6.12.0-160000.6.1, 6.4.0-150600.10.55.1, 6.4.0-150700.7.19.1
dlm-kmp-64kb
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dlm-kmp-azure
6.4.0-150600.8.52.1
dlm-kmp-default
6.12.0-160000.6.1, 6.4.0-150600.23.73.1, 6.4.0-150700.53.19.1
dlm-kmp-rt
6.12.0-160000.6.1, 6.4.0-150600.10.55.1, 6.4.0-150700.7.19.1
dtb-allwinner
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-altera
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-amazon
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-amd
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-amlogic
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-apm
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-apple
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-arm
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-broadcom
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-cavium
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-exynos
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-freescale
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-hisilicon
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
dtb-lg
6.12.0-160000.6.1, 6.4.0-150600.23.73.1
Timeline
Publicly disclosed
Sep 5, 2025
Added to CISA KEV
Sep 18, 2026
Added to Industry KEV feed
Sep 18, 2026
Added to CIRCL KEV
Sep 18, 2026
Added to ENISA EUVD
Sep 18, 2026
Last updated
Oct 15, 2026
Weakness Type
- CWE-754 Improper Check for Unusual or Exceptional Conditions
References
- advisoryRHSA-2025:16880
- advisoryRHSA-2025:16904
- advisoryRHSA-2025:19104
- advisoryRHSA-2025:19223
- advisoryRHSA-2025:19224
FAQ
Common Questions.
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…
Affected: linux-aws-6.12 (chainguard); linux-aws-6.18 (chainguard); linux-azure-6.12 (chainguard), among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Sep 18, 2026.
Yes. It was added on Sep 18, 2026 with a federal remediation due date of Sep 21, 2026.
Public exploit code is available.
Fixed versions are available, including :linux_kernel: :2026-03-05, bpftool 1:6.1.150-174.273.amzn2023, bpftool 6.1.153-1.ph5.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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