Security readout for executives and security teams
Plain-English summary
This is a Linux kernel denial-of-service issue. A local user with some privileges could trigger a NULL pointer dereference in the GRED traffic scheduler during an allocation failure path, potentially crashing the kernel. The impact is availability, not data theft or code execution based on the provided sources.
Executive priority
Treat this as a moderate availability risk. It does not indicate remote compromise or data exposure from the provided evidence, but kernel crashes can disrupt production services. Patch through normal kernel maintenance, with faster handling for shared or high-availability systems.
Technical view
CVE-2025-21980 is a CWE-476 NULL pointer dereference in the Linux kernel GRED scheduler. If kzalloc fails during gred_init, error handling calls gred_destroy, then gred_offload, where memset may receive a NULL table->opt pointer. CVSS 3.1 is 5.5: local, low complexity, low privileges, no user interaction, high availability impact.
Likely exposure
Exposure is mainly Linux systems running affected kernel versions or vendor kernels without the referenced stable fixes. The CVE data lists Linux kernel versions around 5.16 through 6.14 as affected, but distribution backports can change practical exposure.
Exploitation context
The provided sources do not show active exploitation, and KEV is false. Exploitation is local and requires low privileges according to the CVSS vector. The realistic business risk is a kernel crash causing service disruption on multi-user or workload-dense systems.
Researcher notes
The vulnerability is narrowly described as an error-path NULL dereference in GRED offload handling. No exploit details, proof-of-concept, or active exploitation evidence appears in the supplied bundle. Version data is kernel-centric, so distribution-specific exposure requires vendor package mapping.
Mitigation direction
- Apply vendor kernel updates that include the referenced stable fixes.
- Check Linux distribution advisories for backported patched kernel packages.
- Prioritize shared servers, container hosts, and systems with local user access.
- Reduce unnecessary local access while patching is pending.
- Reboot into the patched kernel after package installation.
Validation and detection
- Inventory running Linux kernel versions across affected assets.
- Compare vendor kernel packages against the CVE and stable-fix references.
- Confirm systems booted into the patched kernel after updates.
- Review distribution advisories, including Debian LTS, for package-specific status.
- Monitor for unexplained kernel crashes until remediation is complete.
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-2025-21980 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/d02c9acd68950a444acda18d514e2b41f846cb7fCVE reference, Linux
- https://git.kernel.org/stable/c/0f0a152957d64ce45b4c27c687e7d087e8f45079CVE reference, Linux
- https://git.kernel.org/stable/c/68896dd50180b38ea552e49a6a00b685321e5769CVE reference, Linux
- https://git.kernel.org/stable/c/5f996b4f80c2cef1f9c77275055e7fcba44c9199CVE reference, Linux
- https://git.kernel.org/stable/c/115ef44a98220fddfab37a39a19370497cd718b9CVE reference, Linux
- https://lists.debian.org/debian-lts-announce/2025/05/msg00045.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.
NULL Pointer Dereference
NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.