{"schema_version":"1","data":[{"id":43,"advisory_id":"d33f966d-9fb3-4087-a4d6-f97b264be552","revision":1,"source_id":"core-kev","source_url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2025-39682","source_published_at":"2026-09-18T00:00:00+00:00","published_at":"2026-10-24T20:39:48.110243+00:00","extraction_method":"structured","technologies":["core-kev","kernel"],"cve_ids":["CVE-2025-39682"],"event_types":["advisory"],"payload":{"kind":"advisory","title":"Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability","summary":"Linux Kernel contains an improper check for unusual or exceptional conditions vulnerability in the TLS receive path which allows a zero-length record retrieved from the rx_list to bypass the intended recvmsg() record-type handling, potentially causing subsequent TLS records to be processed using incorrect zero-copy and queuing assumptions. The impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version. 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.","evidence":"kev:CVE-2025-39682","products":[{"name":{"value":"Kernel","evidence":"/product"},"prerequisites":[],"fixed_versions":[],"affected_versions":[]}],"severity":"unknown","structured":{"id":"CVE-2025-39682","aliases":["CVE-2025-39682"],"affected":[],"modified":"2026-09-18T00:00:00.000Z","provider":"kev","references":["https://www.cisa.gov/known-exploited-vulnerabilities-catalog"],"exploitation":{"cwes":["CWE-754"],"cveID":"CVE-2025-39682","notes":"This vulnerability affects an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: ; https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f; https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677; https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9; https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e; https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2025-39682","dueDate":"2026-09-21","product":"Kernel","dateAdded":"2026-09-18","vendorProject":"Linux","requiredAction":"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.","known_exploited":true,"shortDescription":"Linux Kernel contains an improper check for unusual or exceptional conditions vulnerability in the TLS receive path which allows a zero-length record retrieved from the rx_list to bypass the intended recvmsg() record-type handling, potentially causing subsequent TLS records to be processed using incorrect zero-copy and queuing assumptions. The impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version.","vulnerabilityName":"Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability","knownRansomwareCampaignUse":"Unknown"}},"related_cves":[{"value":"CVE-2025-39682","evidence":"/cveID"}],"security_relevant":true,"severity_evidence":null},"priority":{"reasons":["linked_severity","known_exploited"],"severity":"critical","linked_cves":[{"cve":"CVE-2025-39682","metrics":[{"cvssV3_1":{"version":"3.1","baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"scenarios":[{"lang":"en","value":"AV:N - The bug is triggered entirely by the sequence and content of TLS records arriving from the remote peer on a kTLS-enabled TCP socket (net/tls RX path); no local access is needed. Any kTLS RX consumer — OpenSSL-with-kTLS servers/clients, NFS-over-TLS, SMB/RPC-over-TLS via net/handshake — is remotely reachable over the network.\nAC:L - The attacker sends three back-to-back records ([DATA][zero-length non-DATA][DATA]) and the corruption occurs deterministically on the victim's ordinary recvmsg() loop, with no race to win and no memory-layout dependency; the kernel selftest added with the fix reproduces it in one shot. TLS 1.2 is zero-copy-capable by default (zc_capable = rx_no_pad || version != TLS_1_3_VERSION), so no unusual kernel config or sockopt is required.\nPR:N - The attacker is the remote TLS peer, which holds no privileges on the target system — an anonymous client completing a server-authenticated TLS handshake with a kTLS server, or a malicious server that a kTLS client connects to, suffices. This matches the repo's PR:N scoring of the comparable remote-peer net/tls bug CVE-2025-39946.\nUI:N - The victim application only has to run its normal recvmsg() loop on an already-established kTLS socket; no click, mount, file open, or any other victim action is required. The attacker drives the entire trigger from the wire.\nS:U - The corruption is confined to kernel skb/slab state within the same security authority; there is no VM, IOMMU, or sandbox boundary crossed. Standard in-kernel memory corruption is Scope:Unchanged.\nC:H - The strparser anchor is queued on rx_list after tcp_read_done() already released its backing TCP skbs, so the next recvmsg() copies freed kernel heap memory straight into the userspace buffer via skb_copy_datagram_msg(). This is a directly usable, repeatable kernel-memory disclosure primitive, not a bounded pointer leak.\nI:H - The live strp->anchor is consume_skb()'d by process_rx_list() while the strparser still uses it, after which incoming attacker-controlled TCP data is written into the freed sk_buff/skb_shared_info (skb_fill_page_desc, tls_strp_load_anchor_with_queue), and socket teardown double-frees the anchor and its frag_list skbs. This yields attacker-controlled write-after-free and freelist corruption suitable for control-flow hijack.\nA:H - The use-after-free and double-free of the anchor and of already-released TCP receive-queue skbs reliably corrupt slab state, producing oopses/panics and list corruption. Any remote peer can repeat this on every connection, giving a trivial remote kernel-crash DoS."}]}],"products":[{"name":{"value":"Linux","evidence":"/containers/cna/affected/0/product"},"prerequisites":[],"fixed_versions":[],"affected_versions":[]},{"name":{"value":"Linux","evidence":"/containers/cna/affected/1/product"},"prerequisites":[],"fixed_versions":[],"affected_versions":[]}],"severity":"critical","source_id":"core-cve","source_url":"https://www.cve.org/CVERecord?id=CVE-2025-39682","relationship":"advisory","known_exploited":false,"relationship_evidence":"/cveID"}],"fix_available":false,"known_exploited":true,"publisher_severity":"unknown"},"context_update":false}],"next_after":43,"next_before":43}