Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability
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…
Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.
Exploitation probability EPSS · FIRST
Exploitation signals 3 / 5
- KEV catalog (CISA)18 Sept 2026
- Exploited in EUVD (ENISA)18 Sept 2026
- Used by ransomwareno
- EPSS above 10 %3.3%
- No account, over the networkyes
What to do
Fix
Apply the vendor’s fix as soon as it is available.
CISA guidance: 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.
Meanwhile
Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.
Manufacturers (CRA)
Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained
Description ENISA EUVD
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.
Affected products
- patch: 6.1.149
- patch: 0
- 84c61fe1a75b4255df1e1e7c054c9e6d048da417 <c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677
- patch: 6.17
- 84c61fe1a75b4255df1e1e7c054c9e6d048da417 <3439c15ae91a517cf3c650ea15a8987699416ad9
- 84c61fe1a75b4255df1e1e7c054c9e6d048da417 <2902c3ebcca52ca845c03182000e8d71d3a5196f
- 84c61fe1a75b4255df1e1e7c054c9e6d048da417 <62708b9452f8eb77513115b17c4f8d1a22ebf843
- 84c61fe1a75b4255df1e1e7c054c9e6d048da417 <29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e
- patch: 6.12.44
- patch: 6.6.103
- 6.0
- patch: 6.16.4
Open source packages OSV
Affected libraries according to OSV, with fixed versions.
Timeline
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Published
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Exploitation reported (ENISA)
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Added to the KEV catalog
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CISA remediation due date
References
Other exploited vulnerabilities from the same vendor
- CVE-2026-46300Linux Kernel Missing Initialization of a Variable Vulnerability5.4 · Rising fast
- CVE-2026-53266Linux Kernel Out-of-Bounds Write Vulnerability4.7 · Actively exploited
- CVE-2025-39964Linux Kernel Race Condition Vulnerability4.4 · Actively exploited
- CVE-2026-53362Linux Kernel Unspecified Vulnerability4.3 · Actively exploited
- CVE-2022-0995Linux Kernel Out-of-Bounds Write Vulnerability4.6 · Actively exploited
- CVE-2022-0492Linux Kernel Improper Authentication Vulnerability4.5 · Actively exploited