Security readout for executives and security teams
Plain-English summary
This is a Linux kernel denial-of-service flaw in Qualcomm firmware support. A race during EFI variable service registration can trigger a NULL pointer dereference, potentially crashing affected systems. It does not indicate data theft or privilege escalation in the provided sources.
Executive priority
Treat as a routine but real availability risk for affected Qualcomm Linux platforms. Prioritize patching where uptime matters, but there is no source-backed evidence of active exploitation or data compromise.
Technical view
The Qualcomm uefisecapp efivars service could be registered before its memory pool was allocated after TZ allocator changes. A racing EFI variable access may dereference NULL. CVSS is 4.7: local access, high attack complexity, low privileges, no user interaction, availability impact only.
Likely exposure
Exposure is most likely on Linux systems using the Qualcomm uefisecapp EFI variable path in affected kernel builds. The version data is limited, so validate vendor kernels and backports against the referenced stable commits.
Exploitation context
The bundle does not show KEV listing or active exploitation. Exploitation requires local low-privileged access and a timing race, making broad remote exploitation unlikely based on the cited CVSS vector.
Researcher notes
The root issue is resource initialization order: efivars registration occurred before memory pool allocation. Evidence supports a local race-triggered NULL pointer dereference only. Affected-version metadata appears incomplete, so fixed-state confirmation should rely on commit presence or vendor backport notes.
Mitigation direction
- Update to a vendor kernel containing the referenced upstream stable fixes.
- Check distribution or device vendor advisories for backported fixed package versions.
- Prioritize Qualcomm-based devices that expose EFI variable access through this driver.
- Limit untrusted local user access until patched where practical.
- Reboot into the fixed kernel after maintenance approval.
Validation and detection
- Inventory Linux kernel versions across Qualcomm-based systems.
- Confirm whether the qcom uefisecapp efivars driver is present and enabled.
- Compare vendor kernel source or changelog against the three referenced stable commits.
- Review kernel logs for NULL dereference or efivars-related crash evidence.
- Track CVE-2025-21998 status in vendor security advisories.
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-2025-21998 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
- Medium
- CVSS
- 4.7 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:H/PR:L/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.
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:H/PR:L/UI:N/S:U/C:N/I:N/A:H13.6CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
4.7MediumVector: CVSS:3.1/AV:L/AC:H/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/c4e37b381a7a243c298a4858fc0a5a74e737c79aCVE reference, Linux
- https://git.kernel.org/stable/c/f15a2b96a0e41c426c63a932d0e63cde7b9784aaCVE reference, Linux
- https://git.kernel.org/stable/c/da8d493a80993972c427002684d0742560f3be4aCVE 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.