Security readout for executives and security teams
Plain-English summary
CVE-2025-21743 is a Linux kernel flaw in the usbnet ipheth driver. A bad length calculation can overflow and cause the kernel to read outside the expected buffer. Business risk is highest for Linux systems where this driver is present and reachable through local use or attached USB networking paths.
Executive priority
Treat as high priority for Linux endpoint, appliance, and device fleets with USB networking exposure. It is not currently evidenced as exploited here, but kernel out-of-bounds reads can affect confidentiality and availability.
Technical view
The ipheth DPE length check could overflow when wDatagramIndex plus wDatagramLength exceeds U16_MAX, creating an out-of-bounds read condition. The stated fix moves wDatagramIndex to the other side of the inequality. The issue is classified as CWE-125 with CVSS 3.1 score 7.1.
Likely exposure
Exposure is likely limited to Linux systems with affected kernel builds and the usbnet ipheth driver present or usable. The provided version data is not a complete distro matrix, so vendor kernel advisories and backport status must be checked.
Exploitation context
The bundle does not show CISA KEV listing, and no provided source reports active exploitation. CVSS marks the attack vector as local, low complexity, low privilege, no user interaction, with high confidentiality and availability impact.
Researcher notes
The evidence identifies the vulnerable logic and upstream stable commits, but affected-version metadata is sparse and partly ambiguous. Avoid assuming distro exposure from upstream versions alone; confirm with vendor backport records and local kernel configuration.
Mitigation direction
- Update to a Linux kernel containing the referenced stable fix commits.
- Check distribution advisories for backported fixes before relying on upstream version numbers.
- Restrict untrusted local USB/network-device access where operationally feasible.
- Track vendor guidance if running appliance, embedded, or custom kernels.
Validation and detection
- Inventory Linux kernel versions across servers, endpoints, and appliances.
- Check whether the ipheth driver is built, loaded, or available.
- Map installed kernels against distro advisories and the cited stable commits.
- Confirm patched kernels are running after maintenance reboots.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-125: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2025-21743 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
- High
- CVSS
- 7.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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.
SSVC decision data
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:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H1.85.2CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
7.1HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/18bf6f5cce3172cb303c3f0551aa9443d5ed74f8CVE reference, Linux
- https://git.kernel.org/stable/c/d677e7dd59ad6837496f5a02d8e5d39824278dfdCVE reference, Linux
- https://git.kernel.org/stable/c/d824a964185910e317287f034c0a439c08b4fe49CVE reference, Linux
- https://git.kernel.org/stable/c/c219427ed296f94bb4b91d08626776dc7719ee27CVE 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.
Out-of-bounds Read
Out-of-bounds Read represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.