Security readout for executives and security teams
Plain-English summary
A low-privileged local user in a non-initial Linux network namespace could trigger a kernel namespace leak that changes a global TCP congestion-control allowance. The sources rate this high because the CVSS impact claims confidentiality, integrity, and availability risk, but they do not show internet-remote exploitation.
Executive priority
Treat as a high-priority kernel maintenance issue for shared Linux infrastructure. It is not evidenced as actively exploited, but local privilege requirements still matter on container hosts, developer systems, and multi-tenant environments.
Technical view
tcp_set_default_congestion_control() updates a per-network-namespace default but also sets TCP_CONG_NON_RESTRICTED on a global congestion-control algorithm object. That can unintentionally alter the global net.ipv4.tcp_allowed_congestion_control behavior from a non-init namespace, bypassing the intended read-only protection there.
Likely exposure
Exposure is limited to Linux systems running affected kernel versions where an attacker already has local low-privileged access. Risk is more relevant on multi-user hosts and container or namespace-heavy environments using affected kernels.
Exploitation context
The CVE record lists local attack vector, low complexity, low privileges, and no user interaction. The bundle says KEV is false, and no provided source states active exploitation in the wild.
Researcher notes
The core issue is a namespace boundary violation: per-netns default selection has a global side effect on congestion-control restriction flags. The provided sources do not include exploit mechanics, distribution package mappings, or additional mitigations beyond applying fixed kernel code.
Mitigation direction
- Update to a kernel containing the referenced stable fixes.
- Prioritize multi-user and container-host kernels before single-purpose appliances.
- Check distribution vendor advisories for exact fixed package versions.
- Restrict untrusted local access where kernel updates are delayed.
Validation and detection
- Inventory Linux kernel versions across servers and container hosts.
- Compare running kernels against vendor fixed versions or referenced stable commits.
- Identify systems permitting untrusted local users or namespace creation.
- Confirm post-update kernels include the congestion-control namespace fix.
Public sources used
- CVE Program
- CVE List V5
- Linux stable commit 992de06308d9a9584d59b96d294ac676f924e437
- Linux stable commit 9884f745108f7d25b189bbcd6754e284fb29ab68
- Linux stable commit 6c1ea8bee75df8fe2184a50fcd0f70bf82986f42
- Linux stable commit efe1532a6e1a8e3c343d04fff510f0ed80328f9c
- Linux stable commit e7d7bedd507bb732e600403b7a96f9fe48d0ca31
- Linux stable commit 8d432592f30fcc34ef5a10aac4887b4897884493
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
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ATT&CK lookup starting points
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CWE-400: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-47010 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
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: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
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/992de06308d9a9584d59b96d294ac676f924e437CVE reference, Linux
- https://git.kernel.org/stable/c/9884f745108f7d25b189bbcd6754e284fb29ab68CVE reference, Linux
- https://git.kernel.org/stable/c/6c1ea8bee75df8fe2184a50fcd0f70bf82986f42CVE reference, Linux
- https://git.kernel.org/stable/c/efe1532a6e1a8e3c343d04fff510f0ed80328f9cCVE reference, Linux
- https://git.kernel.org/stable/c/e7d7bedd507bb732e600403b7a96f9fe48d0ca31CVE reference, Linux
- https://git.kernel.org/stable/c/8d432592f30fcc34ef5a10aac4887b4897884493CVE 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.
Uncontrolled Resource Consumption
Uncontrolled Resource Consumption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.