Security readout for executives and security teams
Plain-English summary
This Linux kernel flaw can let a local low-privileged user cause an affected 32-bit system using XFS to hang in an infinite loop. The business impact is availability, not data theft or tampering. It matters most for shared servers, appliances, or legacy 32-bit deployments where untrusted users or workloads can write to XFS filesystems.
Executive priority
Treat as a targeted availability risk, not a broad remote compromise issue. Patch during normal security maintenance, but accelerate on shared 32-bit XFS systems where local users or workloads are not fully trusted.
Technical view
On 32-bit kernels, folio_seek_hole_data() truncates a 64-bit offset to 32 bits. The CVE states this can create an infinite loop when writing to an XFS filesystem. CVSS is 5.5 with local access, low complexity, low privileges, no user interaction, and high availability impact only.
Likely exposure
Exposure appears limited to affected Linux kernel builds on 32-bit systems, especially those using XFS. Internet-facing exposure is not indicated by the sources because the attack vector is local. Cloud, container, and appliance risk depends on whether tenants or local users can write to an affected host filesystem.
Exploitation context
The source bundle does not show active exploitation, and KEV is false. The documented path is local denial of service through the kernel filesystem behavior. Sources do not provide exploit details, public weaponization evidence, or remote attack claims.
Researcher notes
Evidence supports CWE-835 infinite loop caused by integer truncation in folio_seek_hole_data() on 32-bit kernels. The CVE references multiple Linux stable commits and a Debian LTS advisory. The bundle does not provide complete product-specific package versions across all distributions.
Mitigation direction
- Apply Linux stable or distribution kernel updates that include the referenced fixes.
- Prioritize 32-bit systems, shared hosts, and systems using XFS.
- Use distribution security advisories when vendor kernels backport fixes without changing major versions.
- If no package is available, track vendor guidance for CVE-2025-21665.
- Reduce local untrusted write access to affected XFS filesystems where practical.
Validation and detection
- Inventory Linux hosts for 32-bit kernels and XFS filesystem usage.
- Check vendor advisories or package changelogs for CVE-2025-21665.
- Confirm the running kernel includes the relevant stable fix or vendor backport.
- Validate reboot completion where kernel package installation requires it.
- Review monitoring for unexplained hangs on affected legacy systems.
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-835: 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-2025-21665 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
- 5.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/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:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6CISA-ADPVulnerability scoring details
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/64e5fd96330df2ad278d1c4edcca581f26e5f76eCVE reference, Linux
- https://git.kernel.org/stable/c/80fc836f3ebe2f2d2d2c80c698b7667974285a04CVE reference, Linux
- https://git.kernel.org/stable/c/09528bb1a4123e2a234eac2bc45a0e51e78dab43CVE reference, Linux
- https://git.kernel.org/stable/c/280f1fb89afc01e7376f59ae611d54ca69e9f967CVE reference, Linux
- https://git.kernel.org/stable/c/f505e6c91e7a22d10316665a86d79f84d9f0ba76CVE reference, Linux
- https://lists.debian.org/debian-lts-announce/2025/03/msg00001.htmlCVE reference, CVE
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.
Loop with Unreachable Exit Condition ('Infinite Loop')
Loop with Unreachable Exit Condition ('Infinite Loop') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.