Security readout for executives and security teams
Plain-English summary
A Linux GPIO virtual-user cleanup flaw can leave stale lookup data after failed device setup and leak memory during repeated state changes. This can prevent corrected configurations from working until the device is released. The supplied CVSS rating is 7.8 (high), although the source description primarily documents reliability and resource-cleanup effects.
Executive priority
Prioritize affected systems that actively expose GPIO virtuser configuration, especially shared or sensitive hosts. Patch through normal high-severity kernel maintenance. Systems not using this functionality appear less exposed, but version ambiguity warrants vendor confirmation before deferral.
Technical view
The gpio virtuser driver failed to remove lookup tables after an invalid-table probe failure or platform-device registration failure. It also consistently leaked lookup_table->dev_id when toggling live state. The fix adds gpio_virtuser_remove_lookup_table() and invokes it along all necessary cleanup paths. The supplied vector requires local access and low privileges, without user interaction.
Likely exposure
Exposure requires an affected Linux kernel and use of the GPIO virtuser device through configfs. The bundle flags Linux 6.11, 6.12.10, and 6.13, but its version data is ambiguous and includes an unexplained “0.” Confirm exact affected ranges and distribution backports with the kernel vendor.
Exploitation context
The bundle does not identify this CVE in CISA KEV and provides no evidence of active exploitation or a public exploit. The described trigger is local interaction with a virtuser configfs device. Treat claims of remote or in-the-wild exploitation as unsupported by these sources.
Researcher notes
CWE-401 applies to the reported unreleased memory. Documented effects include stale lookup-table state, failed subsequent probes, and a repeatable dev_id leak. The supplied CVSS claims high confidentiality, integrity, and availability impacts, but the narrative does not explain those broader consequences; further impact claims would require additional evidence.
Mitigation direction
- Install a vendor kernel containing either referenced stable-kernel fix or an equivalent backport.
- Check distribution security guidance for precise affected and fixed package versions.
- Limit access to systems and workflows that configure GPIO virtuser devices through configfs.
- Avoid repeated live-state toggling until remediation if GPIO virtuser is operationally required.
Validation and detection
- Inventory kernel versions and identify systems using GPIO virtuser devices through configfs.
- Verify the installed kernel includes either cited fix commit or a vendor-confirmed equivalent backport.
- Confirm failed probes no longer leave lookup tables that block corrected probe attempts.
- Monitor memory behavior during authorized live-state cycling to confirm the reported leak is resolved.
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-401: 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-2025-21661 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/d72d0126b1f6981f6ce8b4247305f359958c11b5CVE reference, Linux
- https://git.kernel.org/stable/c/a619cba8c69c434258ff4101d463322cd63e1bdcCVE 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.
Missing Release of Memory after Effective Lifetime
Missing Release of Memory after Effective Lifetime represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.