Security readout for executives and security teams
Plain-English summary
A flaw in the Linux kernel’s SCTP networking code can dereference a null event pointer under specific association conditions, potentially crashing the system. The supplied CVSS assessment rates it 7.5 because an unauthenticated network actor may cause loss of availability; no confidentiality or integrity impact is identified.
Executive priority
Prioritize internet-facing or business-critical Linux systems using SCTP. Treat remediation as an availability-protection task: validate actual SCTP exposure, obtain distribution-specific fixed packages, and patch promptly. Systems without SCTP exposure may be scheduled through normal risk-based maintenance after verification.
Technical view
During SCTP association processing in sctp_sf_do_5_1D_ce(), particular adaptation-indication and authentication-key event conditions can leave ai_ev null. The code subsequently passes that null pointer to sctp_ulpevent_free(), causing a kernel null-pointer dereference. Linux stable commits are supplied for multiple maintained kernel branches.
Likely exposure
Exposure is most relevant to systems running affected Linux kernels where SCTP is present and network-reachable. The bundle lists versions beginning with 4.17 and several later version markers, but its flattened version data does not clearly express every fixed range. Distribution backports must be checked separately.
Exploitation context
The network-accessible, low-complexity, unauthenticated CVSS vector supports denial-of-service risk. The bundle marks this CVE as absent from KEV and provides no evidence of active exploitation or public weaponization.
Researcher notes
The supplied description appears internally inconsistent around sctp_ulpevent_make_authkey, but the core failure is clear: ai_ev can remain null and later be freed. Exact affected-to-fixed ranges are not reliably recoverable from the flattened version list; inspect the CVE record and applicable stable-branch commit or distribution advisory.
Mitigation direction
- Apply the appropriate vendor kernel update containing the relevant Linux stable fix.
- Check distribution advisories for backported fixes rather than relying only on upstream version numbers.
- Until patched, reduce unnecessary network exposure of SCTP according to vendor operational guidance.
- Schedule any required reboot so the corrected kernel becomes active.
Validation and detection
- Record each system’s running kernel version, not only its installed package version.
- Determine whether SCTP is present, used, and reachable from untrusted networks.
- Verify the vendor kernel includes a backport matching the applicable stable fix commit.
- After maintenance, confirm systems booted into the corrected kernel.
- Review kernel logs for SCTP-related null dereferences or unexplained availability events.
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
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ATT&CK lookup starting points
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CVE-2025-40187 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:N/I:N/A:H3.93.6LinuxVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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/1014b83778c8677f1d7a57c26dc728baa801ac62CVE reference, Linux
- https://git.kernel.org/stable/c/7f702f85df0266ed7b5bab81ba50394c92f3c928CVE reference, Linux
- https://git.kernel.org/stable/c/dbceedc0213e75bf3e9f9f9e2f66b10699d004feCVE reference, Linux
- https://git.kernel.org/stable/c/025419f4e216a3ae0d0cec622262e98e8078c447CVE reference, Linux
- https://git.kernel.org/stable/c/c21f45cfa4a9526b34d76b397c9ef080668b6e73CVE reference, Linux
- https://git.kernel.org/stable/c/d0e8f1445c19b1786759ba72a38267e1449bab7eCVE reference, Linux
- https://git.kernel.org/stable/c/badbd79313e6591616c1b78e29a9b71efed7f035CVE reference, Linux
- https://git.kernel.org/stable/c/2f3119686ef50319490ccaec81a575973da98815CVE 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.