Security readout for executives and security teams
Plain-English summary
A Linux kernel flaw in the Steam HID driver can access freed memory when a device is detached. A local low-privileged user may trigger the condition without user interaction, potentially causing a crash or broader system compromise. Exposure depends on whether affected systems use the hid-steam driver and related devices.
Executive priority
Prioritize affected multi-user endpoints and systems where untrusted users can access Steam-compatible HID hardware. Treat remediation as high priority, but scope first because exploitation is local and depends on the relevant driver and device workflow.
Technical view
Cleanup ordering allowed deferred input-device reattachment work to be rescheduled after cancellation while client_hdev was being destroyed, producing a use-after-free. The fix cleans up client_hdev before ensuring deferred work is canceled. CVSS 3.1 is 7.8 with local, low-complexity, low-privilege access and high confidentiality, integrity, and availability impacts.
Likely exposure
Most relevant to Linux endpoints or specialized systems using the hid-steam driver where a related HID device can be detached. The supplied data does not clearly define complete vulnerable version ranges, so exposure cannot be determined from version numbers alone.
Exploitation context
The supplied CVSS indicates exploitation requires local access and low privileges, with no user interaction. The CVE is not listed as KEV, and the sources provide no evidence of active exploitation or a public exploit.
Researcher notes
CWE-416 applies. The source bundle lists versions and commit identifiers but does not provide an unambiguous vulnerable-version range. Analysis should focus on backport presence, driver use, device-detachment reachability, and deferred-work lifecycle behavior. No exploitation evidence is supplied.
Mitigation direction
- Update to a vendor-supported kernel release containing the applicable stable fix.
- Compare vendor kernel patches against the four referenced upstream stable commits.
- If immediate updating is impossible, restrict local access and unnecessary use of affected Steam HID devices.
- Monitor Linux distribution advisories for precise vulnerable and corrected package versions.
Validation and detection
- Inventory systems loading or using the hid-steam driver.
- Record kernel and distribution package versions on potentially exposed systems.
- Confirm the installed kernel contains the applicable stable fix through vendor documentation or patch history.
- Test device detachment safely after updating and monitor for kernel memory or crash reports.
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-416: 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-2025-21923 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:H/I:H/A:H1.85.9CISA-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
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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/026714ec7546de741826324a6a1914c91024d06cCVE reference, Linux
- https://git.kernel.org/stable/c/a899adf7063c6745aaff1ec869f3c7f6329ed0a1CVE reference, Linux
- https://git.kernel.org/stable/c/ea3f18d2f02629653b7bfe42607737ccd1343e54CVE reference, Linux
- https://git.kernel.org/stable/c/e53fc232a65f7488ab75d03a5b95f06aaada7262CVE 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.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.