Security readout for executives and security teams
Plain-English summary
A Linux kernel TLS receive-path flaw can mishandle unfinished asynchronous decryption when a memory allocation fails. This may cause use-after-free behavior or writes into application memory after a receive call completes, threatening confidentiality, integrity, and availability. The supplied CVSS score is 9.8, but practical reachability depends on kernel version and use of the affected TLS path.
Executive priority
Treat as an urgent verification and patching item because the potential impact includes memory-safety failure across confidentiality, integrity, and availability. Prioritize confirmed kernel TLS users and exposed systems. Do not infer an active emergency solely from the 9.8 score: the supplied evidence does not establish exploitation in the wild.
Technical view
During asynchronous TLS decryption, tls_strp_msg_hold clones the input socket buffer to preserve referenced memory. If cloning fails, processing could continue while decryption remains pending, permitting an skb use-after-free or a delayed write into userspace memory. The referenced kernel changes resolve this by waiting for pending decryption requests after that failure.
Likely exposure
Potential exposure is limited to Linux systems containing an affected kernel revision and exercising the relevant kernel TLS asynchronous receive-decryption path. The supplied affected-version metadata is ambiguous and includes isolated version identifiers rather than clear distribution package ranges. Confirm exposure against each Linux distributor's mapping of the referenced upstream fixes.
Exploitation context
The supplied record assigns CVSS 3.1 score 9.8 with network reachability, low complexity, no privileges, and no user interaction. However, it provides no evidence of public exploitation, exploit availability, or CISA KEV listing. Treat the score as a severity signal, not proof that every affected host is remotely exploitable in practice.
Researcher notes
The failure condition is an unsuccessful socket-buffer clone while asynchronous decryptions remain pending. Documented consequences include skb use-after-free and writes into userspace after recv() returns. The supplied data does not establish exploitability prerequisites, affected distribution builds, reliable attack reachability, or a CWE. Analyze referenced patches and distributor backports before making stronger claims.
Mitigation direction
- Install a vendor-supported kernel package containing the applicable referenced upstream fix.
- Prioritize internet-facing or sensitive systems using kernel TLS receive processing.
- Consult Linux distribution advisories for precise affected and fixed package versions.
- If immediate updating is impossible, assess whether affected kernel TLS functionality can be safely avoided.
Validation and detection
- Inventory running kernel versions across Linux hosts and containers sharing host kernels.
- Determine whether workloads enable or depend upon kernel TLS receive processing.
- Map distribution kernel packages to the five referenced upstream correction commits.
- After updating, verify the running kernel—not merely the installed package—contains the vendor fix.
- Review vendor advisories for backports that may not match upstream version numbers.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CVE-2025-40176 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9LinuxVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/9f83fd0c179e0f458e824e417f9d5ad53443f685CVE reference, Linux
- https://git.kernel.org/stable/c/c61d4368197d65c4809d9271f3b85325a600586aCVE reference, Linux
- https://git.kernel.org/stable/c/39dec4ea3daf77f684308576baf483b55ca7f160CVE reference, Linux
- https://git.kernel.org/stable/c/4fc109d0ab196bd943b7451276690fb6bb48c2e0CVE reference, Linux
- https://git.kernel.org/stable/c/b8a6ff84abbcbbc445463de58704686011edc8e1CVE reference, Linux
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.