Security readout for executives and security teams
Plain-English summary
A Linux kernel flaw in the Broadcom NetXtreme-E RDMA driver can dereference already-freed device state when interrupt callbacks occur after detachment, causing a system crash. Exposure appears limited to systems using the affected bnxt_re driver and vulnerable kernel code.
Executive priority
Remediate promptly on affected RDMA hosts, especially systems supporting latency-sensitive or highly available services. Broad fleet emergency action is not justified without confirming bnxt_re exposure. There is no cited evidence of active exploitation, but successful triggering could cause material service interruption.
Technical view
CVE-2025-21901 is a CWE-476 NULL-pointer dereference in RDMA/bnxt_re. The ulp_irq_stop or ulp_irq_start callbacks may run after device detachment, when rdev has already been freed. The kernel fixes add validity checks. The supplied record assigns CVSS 3.1 score 7.8 with local, low-privilege access required.
Likely exposure
Prioritize Linux hosts using Broadcom bnxt_re RDMA functionality. The source bundle identifies affected 6.12-era and later version entries, but its version encoding is ambiguous; confirm exact exposure through distribution advisories and fix-backport records rather than version numbers alone.
Exploitation context
The bundle does not identify CISA KEV inclusion, active exploitation, or a public exploit. The CVSS vector describes local, low-complexity exploitation requiring low privileges and no user interaction. Available technical text establishes a crash condition but does not explain how the scored confidentiality and integrity impacts would occur.
Researcher notes
The documented defect is a use-after-free state leading to NULL-pointer dereference, although the assigned CWE is CWE-476. The supplied narrative supports denial of service through a kernel crash. It does not establish code execution or explain confidentiality and integrity impact. Exact affected release boundaries require vendor confirmation because the bundled version entries are unclear.
Mitigation direction
- Install a supported vendor kernel containing the applicable cited stable fix.
- Check Linux distribution advisories for exact vulnerable and fixed package versions.
- Prioritize RDMA-enabled production systems where a kernel crash would disrupt critical services.
- Follow vendor guidance if an updated kernel is not immediately available.
Validation and detection
- Identify hosts with Broadcom RDMA hardware or the bnxt_re driver in use.
- Record installed kernel and distribution package versions on potentially exposed hosts.
- Confirm vendor changelogs include a cited fix commit or an explicit CVE backport.
- After updating, verify the corrected kernel is running following any required reboot.
- Review kernel logs for bnxt_re faults or unexplained crashes around device detach 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
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-476: 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-2025-21901 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
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/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.
SSVC decision data
CVSS vector scores
2 official scoresWe 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:H/A:H1.85.9LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Base CVSS 3.1 score
5.5MediumVector: CVSS:3.1/AV:L/AC:L/PR:L/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.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/aed1bc673907e3df372b317c10ff2f3582f8bf1aCVE reference, Linux
- https://git.kernel.org/stable/c/8cb0eef46d70a99c88c26a1addb7fd955242e0e6CVE reference, Linux
- https://git.kernel.org/stable/c/f0df225d12fcb049429fb5bf5122afe143c2dd15CVE 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.
NULL Pointer Dereference
NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.