Security readout for executives and security teams
Plain-English summary
This is a Linux kernel nftables memory-safety bug. During set destruction, the kernel could read a catchall set entry after it was freed. The source bundle shows a kernel fix and a syzbot/KASAN crash report, but no confirmed real-world exploitation.
Executive priority
Treat as a kernel patch-management item with uncertain exploitability. Prioritize systems where kernel compromise or denial of service would have high business impact, but do not claim emergency active exploitation from the provided evidence.
Technical view
CVE-2021-47106 affects Linux nf_tables. nft_set_catchall_destroy() used an unsafe list iterator after kfree_rcu(), causing a use-after-free during nft_set_destroy() and table release paths. The kernel fix switches to safe iteration. Affected version data in the bundle includes Linux 5.13, 5.15.12, and 5.16.
Likely exposure
Exposure is most relevant on Linux systems running affected kernels with nf_tables/netfilter available. The bundle does not establish whether remote, local, privileged, or containerized attack paths are viable, so access requirements should be validated against vendor advisories and deployed kernel configuration.
Exploitation context
The evidence is a syzbot/KASAN report and upstream stable kernel fixes. The bundle marks KEV as false and provides no cited evidence of active exploitation or public weaponization.
Researcher notes
The source bundle identifies the vulnerable path and root cause, but omits CVSS, CWE, exploitation prerequisites, and impact boundaries. Research should focus on affected kernel lineage, distro backports, and whether nftables operations require privileges in each environment.
Mitigation direction
- Update affected Linux kernels to versions containing the referenced stable fixes.
- Check Linux distribution advisories for backported package versions.
- Prioritize internet-facing and multi-tenant Linux hosts for kernel review.
- Track vendor guidance before applying compensating controls.
- Avoid direct wrangler or deployment assumptions; this is kernel remediation work.
Validation and detection
- Record kernel versions across Linux assets.
- Compare installed kernel packages with vendor-fixed versions.
- Confirm whether nf_tables is enabled or used on priority systems.
- Review change logs for the two referenced stable commits.
- Verify patched hosts after reboot into the updated kernel.
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.
CVE-2021-47106 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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
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/9d558e5f0d6fdd0a568f73dceb0b40c4f5012e5aCVE reference, Linux
- https://git.kernel.org/stable/c/0f7d9b31ce7abdbb29bf018131ac920c9f698518CVE 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.