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ExploitedIn CISA KEVFix available

CVE-2025-39682

Exploitation confirmed. First attested on 2026-09-18 by CISA-ADP, CISA KEV, GCVE · previdian.

  • Published2025-09-05
  • Fixed in6.16.4 · 6.12.44 · 6.6.103 · 6.1.149
  • WeaknessCWE-754

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2025-09-0518:15CVE publishedNVD
  2. 2026-09-18Added to the CISA KEV catalogCISA KEV
  3. 2026-09-18Listed as exploited by GCVEGCVE
  4. 2026-09-18Exploitation first reportedCISA KEV
  5. 2026-09-1903:56SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2025-39682?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2025-39682?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Linux linux kernel
BranchAffectedFixed in
6.x≥ 6.13, < 6.16.46.16.4
6.x≥ 6.13.0, < 6.16.46.16.4
6.x≥ 6.7, < 6.12.446.12.44
6.x≥ 6.7.0, < 6.12.446.12.44
6.x≥ 6.2, < 6.6.1036.6.103
6.x≥ 6.2.0, < 6.6.1036.6.103
6.x≥ 6.0, < 6.1.1496.1.149
6.x≥ 6.0.0, < 6.1.1496.1.149
6.17= 6.17no fix published
Debian debian linux
BranchAffectedFixed in
11.0= 11.0no fix published
Siemens simatic cn 4100 firmwareversion to verify
BranchAffectedFixed in
5.0< 5.05.0

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA2 products

As Linux, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • Linuxother versions: not affected

    https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

    Affected
    • ≥ 84c61fe1a75b4255df1e1e7c054c9e6d048da417, < 2902c3ebcca52ca845c03182000e8d71d3a5196ffixed in 2902c3ebcca52ca845c03182000e8d71d3a5196fgit
    • ≥ 84c61fe1a75b4255df1e1e7c054c9e6d048da417, < c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677fixed in c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677git
    • ≥ 84c61fe1a75b4255df1e1e7c054c9e6d048da417, < 3439c15ae91a517cf3c650ea15a8987699416ad9fixed in 3439c15ae91a517cf3c650ea15a8987699416ad9git
    • ≥ 84c61fe1a75b4255df1e1e7c054c9e6d048da417, < 29c0ce3c8cdb6dc5d61139c937f34cb888a6f42efixed in 29c0ce3c8cdb6dc5d61139c937f34cb888a6f42egit
    • ≥ 84c61fe1a75b4255df1e1e7c054c9e6d048da417, < 62708b9452f8eb77513115b17c4f8d1a22ebf843fixed in 62708b9452f8eb77513115b17c4f8d1a22ebf843git
  • Linuxother versions: affected

    https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

    Affected
    • = 6.0no fix stated

    Not affected < 6.0 · ≥ 6.1.149, ≤ 6.1.* · ≥ 6.6.103, ≤ 6.6.* · ≥ 6.12.44, ≤ 6.12.* · ≥ 6.16.4, ≤ 6.16.* · ≥ 6.17

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-08-05

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • :linux_kernel:Androidfrom :0 · fixed in :2026-03-05
  • bpftoolTuxCare:AlmaLinux:9.2all versions · fixed in 7.0.0-284.1101.el9_2.tuxcare.11.els15
  • bpftoolRed Hat:rhel_eus:9.4::baseosall versions · fixed in 0:7.3.0-427.96.1.el9_4and 1 other package
  • bpftoolRed Hat:rhel_e4s:9.2::baseosall versions · fixed in 0:7.0.0-284.144.1.el9_2and 1 other package
  • bpftool-debuginfoRed Hat:rhel_eus:9.4::realtimeall versions · fixed in 0:7.3.0-427.96.1.el9_4
  • bpftool-debuginfoRed Hat:rhel_eus:9.4::nfvall versions · fixed in 0:7.3.0-427.96.1.el9_4
  • bpftool-debuginfoRed Hat:rhel_eus:9.4::crball versions · fixed in 0:7.3.0-427.96.1.el9_4
  • bpftool-debuginfoRed Hat:rhel_eus:9.4::appstreamall versions · fixed in 0:7.3.0-427.96.1.el9_4

170 more package ranges on OSV.dev

Vendor advisories

  • CVE-2025-39682 Red Hat Product Security1,092 products fixed

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

  • RHSA-2025:19224 Red Hat Product Security167 products fixed

    Red Hat Security Advisory: kernel security update

  • RHSA-2025:19223 Red Hat Product Security34 products fixed

    Red Hat Security Advisory: kernel-rt security update

  • RHSA-2025:19104 Red Hat Product Security279 products fixed

    Red Hat Security Advisory: kernel security update

  • RHSA-2025:16904 Red Hat Product Security307 products fixed

    Red Hat Security Advisory: kernel security update

  • RHSA-2025:16880 Red Hat Product Security305 products fixed

    Red Hat Security Advisory: kernel security update

Full record on NVD

Fix

  1. Update Linux linux kernel to 6.16.4 · 6.12.44 · 6.6.103 · 6.1.149
  2. CISA’s 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.due 2026-09-21
  3. Vendor fix Red Hat Product Security RHSA-2025:19224 · 167 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 The system must be rebooted for this update to take effect.
  4. Workaround from the vendor Red Hat Product Security RHSA-2025:19224 · 167 productsTo mitigate this issue, prevent module tls from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.

Advisories and patches

Detection

read 2026-11-03 22:42 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
2 repositories, unverifiedkhoatran107/cve-2025-39682suominen/CVE-2025-39682
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2026-09-18
Patch Due Date
2026-09-21
Ransomware Use
Unknown
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.

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2025-09-05
Last Modified
2026-10-19
NVD status
Analyzed
GitHub Advisory
GHSA-v2pf-75pf-9c5h

Frequently asked questions

What is CVE-2025-39682?

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.

Is CVE-2025-39682 actively exploited?

Yes. CVE-2025-39682 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2026-09-21.

What is the CVSS score for CVE-2025-39682?

CVE-2025-39682 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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