Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
AV AC PR UI S C I A CVSS EPSS %ile KEV L L L N U N N H 5.5 .0023 14.4 —
AFFECTED Product Versions Fixed Linux 9cb8e048e5d93825ec5e8dfb5b8df4987ea25745 – — Linux 5.7 – 5.10.32
TIMELINE Feb 25 Reserved by Linux Feb 27 Published (CNA: Linux) Aug 4 RESCORED — CVE-2021-46912 (Linux). CVSS 7.3 → 5.5 (NVD).
In the Linux kernel, the following vulnerability has been resolved: net: Make tcp_allowed_congestion_control readonly in non-init netns Currently, tcp_allowed_congestion_control is global and writable; writing to it in any net namespace will leak into all other net namespaces. tcp_available_congestion_control and tcp_allowed_congestion_control are the only sysctls in ipv4_net_table (the per-netns sysctl table) with a NULL data pointer; their handlers (proc_tcp_available_congestion_control and proc_allowed_congestion_control) have no other way of referencing a struct net. Thus, they operate globally. Because ipv4_net_table does not use designated initializers, there is no easy way to fix up this one "bad" table entry. However, the data pointer updating logic shouldn't be applied to NULL pointers anyway, so we instead force these entries to be read-only. These sysctls used to exist in ipv4_table (init-net only), but they were moved to the per-net ipv4_net_table, presumably without realizing that tcp_allowed_congestion_control was writable and thus introduced a leak. Because the intent of that commit was only to know (i.e. read) "which congestion algorithms are available or allowed", this read-only solution should be sufficient. The logic added in recent commit 31c4d2f160eb: ("net: Ensure net namespace isolation of sysctls") does not and cannot check for NULL data pointers, because other table entries (e.g. /proc/sys/net/netfilter/nf_log/) have .data=NULL but use other methods (.extra2) to access the struct net.
| Date | Event | Detail |
|---|---|---|
| February 25, 2024 | Reserved | Reserved by Linux |
| February 27, 2024 | Published | Published (CNA: Linux) |
| August 4, 2026 | RESCORED | RESCORED — CVE-2021-46912 (Linux). CVSS 7.3 → 5.5 (NVD). |
Authoritative record: CVE-2021-46912 at cve.org
Vendors: linux
Weaknesses: CWE-476
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-46912 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.