CVE-2021-47010
net: Only allow init netns to set default tcp cong to a restricted algo
- Published
- Updated
- Reserved
- Assigned by
- Linux
Description
In the Linux kernel, the following vulnerability has been resolved: net: Only allow init netns to set default tcp cong to a restricted algo tcp_set_default_congestion_control() is netns-safe in that it writes to &net->ipv4.tcp_congestion_control, but it also sets ca->flags |= TCP_CONG_NON_RESTRICTED which is not namespaced. This has the unintended side-effect of changing the global net.ipv4.tcp_allowed_congestion_control sysctl, despite the fact that it is read-only: 97684f0970f6 ("net: Make tcp_allowed_congestion_control readonly in non-init netns") Resolve this netns "leak" by only allowing the init netns to set the default algorithm to one that is restricted. This restriction could be removed if tcp_allowed_congestion_control were namespace-ified in the future. This bug was uncovered with https://github.com/JonathonReinhart/linux-netns-sysctl-verify
Timeline
ID reserved
By Linux
- 1 day later
· 1 day later
Published
- 2 years later
· 2 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADPADP (enrichment) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Analyzed | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.26% · top 83% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Weakness
Affected products
- affected 6670e152447732ba90626f36dfc015a13fbf150e – < 992de06308d9a9584d59b96d294ac676f924e437
- affected 6670e152447732ba90626f36dfc015a13fbf150e – < 9884f745108f7d25b189bbcd6754e284fb29ab68
- affected 6670e152447732ba90626f36dfc015a13fbf150e – < 6c1ea8bee75df8fe2184a50fcd0f70bf82986f42
- affected 6670e152447732ba90626f36dfc015a13fbf150e – < efe1532a6e1a8e3c343d04fff510f0ed80328f9c
- affected 6670e152447732ba90626f36dfc015a13fbf150e – < e7d7bedd507bb732e600403b7a96f9fe48d0ca31
- affected 6670e152447732ba90626f36dfc015a13fbf150e – < 8d432592f30fcc34ef5a10aac4887b4897884493
- affected 4.15
- unaffected < 4.15
- unaffected 4.19.191 – ≤ 4.19.*
- unaffected 5.4.119 – ≤ 5.4.*
- unaffected 5.10.37 – ≤ 5.10.*
- unaffected 5.11.21 – ≤ 5.11.*
- unaffected 5.12.4 – ≤ 5.12.*
- unaffected 5.13 – ≤ *
References (6)
- https://git.kernel.org/stable/c/992de06308d9a9584d59b96d294ac676f924e437 (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/9884f745108f7d25b189bbcd6754e284fb29ab68 (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/6c1ea8bee75df8fe2184a50fcd0f70bf82986f42 (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/efe1532a6e1a8e3c343d04fff510f0ed80328f9c (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/e7d7bedd507bb732e600403b7a96f9fe48d0ca31 (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/8d432592f30fcc34ef5a10aac4887b4897884493 (opens in a new tab)x_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2021-47010)Record last updated .