VULNpocalypse

CVE-2025-39682: Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

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.

Description quoted from the CVE record (assigned by Linux, published 2025-09-05).

Weakness: CWE-754 Improper Check for Unusual or Exceptional Conditions

How it can be exploited

Exploitable over the network with low attack complexity needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.

On CISA KEV since
2026-09-18
US federal deadline
2026-09-21
Ransomware use
Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2025-12988, CNNVD-202509-770, EUVD-2025-31542, GHSA-v2pf-75pf-9c5h

VEDAS cluster: VEDAS:ASCENTAURA

Exploit Observer links 2 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (2)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Vulnerability databases and vendor advisories (11)

Catalogue entries, not exploit evidence.

News (1)

102 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
0.033
some chance of attack soon
VEDAS
0.968
strong exploit evidence
On CISA KEV
Yes, since 2026-09-18
Detection rule
None yet
EPSS (chance of attack)
10No cve-scores data 2026-02-22 to 2026-08-08no data0.1Added to CISA KEV 2026-09-18CVE-2025-39682 EPSS over time2025-092026-11-01
VEDAS (exploit evidence)
10No cve-scores data 2026-02-22 to 2026-08-08no data0.9Added to CISA KEV 2026-09-18CVE-2025-39682 VEDAS over time2025-092026-11-01

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish. The vertical line is the day CISA added it to its exploited list.

VEDAS flagged this bug about 28 days before CISA confirmed attacks.

Who is affected

ProductAffectedNot affected
Linux Linuxfrom 84c61fe1a75b before 2902c3ebcca5 (git commit)
from 84c61fe1a75b before c09dd3773b59 (git commit)
from 84c61fe1a75b before 3439c15ae91a (git commit)
from 84c61fe1a75b before 29c0ce3c8cdb (git commit)
from 84c61fe1a75b before 62708b9452f8 (git commit)		Not stated
Linux Linuxversion 6.00 is not affected (up to 6.0); 6.1.149 is not affected; 6.6.103 is not affected; 6.12.44 is not affected

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: debian debian_linux, linux linux_kernel.

How to fix it

CISA 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.

Vendor guidance:

How to detect it

There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.

References

Government sources

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.