Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2021-46912— net: Make tcp_allowed_congestion_control readonly in non-init netns

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 tcp_allowed_congestion_control 存在泄露问题。

CVSS 7.3 · High EPSS 0.24% · P13

Possible ATT&CK Techniques 1 AI

T1557 · Adversary-in-the-Middle

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 9cb8e048e5d93825ec5e8dfb5b8df4987ea25745< 35d7491e2f77ce480097cabcaf93ed409e916e12 affected
9cb8e048e5d93825ec5e8dfb5b8df4987ea25745< 1ccdf1bed140820240e383ba0accc474ffc7f006 affected
9cb8e048e5d93825ec5e8dfb5b8df4987ea25745< 97684f0970f6e112926de631fdd98d9693c7e5c1 affected
5.7 affected
< 5.7 unaffected
5.10.32≤ 5.10.* unaffected
5.11.16≤ 5.11.* unaffected
5.12≤ * unaffected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2021-46912

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
net: Make tcp_allowed_congestion_control readonly in non-init netns
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 tcp_allowed_congestion_control 存在泄露问题。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 9cb8e048e5d93825ec5e8dfb5b8df4987ea25745 ~ 35d7491e2f77ce480097cabcaf93ed409e916e12 -
Linux Linux 5.7 -

II. Public POCs for CVE-2021-46912

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2021-46912

请登录查看更多情报信息。

Other References for CVE-2021-46912 (3)

Same Patch Batch · Linux · 2024-02-27 · 67 CVEs total

CVE-2021-46911 9.8 CRITICAL ch_ktls: Fix kernel panic
CVE-2021-46955 8.2 HIGH openvswitch: fix stack OOB read while fragmenting IPv4 packets
CVE-2021-46936 7.8 HIGH net: fix use-after-free in tw_timer_handler
CVE-2021-46973 7.8 HIGH net: qrtr: Avoid potential use after free in MHI send
CVE-2021-46913 7.8 HIGH netfilter: nftables: clone set element expression template
CVE-2021-46969 7.8 HIGH bus: mhi: core: Fix invalid error returning in mhi_queue
CVE-2021-46967 7.8 HIGH vhost-vdpa: fix vm_flags for virtqueue doorbell mapping
CVE-2021-46921 7.8 HIGH locking/qrwlock: Fix ordering in queued_write_lock_slowpath()
CVE-2021-46925 7.8 HIGH net/smc: fix kernel panic caused by race of smc_sock
CVE-2021-46963 7.8 HIGH scsi: qla2xxx: Fix crash in qla2xxx_mqueuecommand()
CVE-2021-46929 7.8 HIGH sctp: use call_rcu to free endpoint
CVE-2021-46958 7.8 HIGH btrfs: fix race between transaction aborts and fsyncs leading to use-after-free
CVE-2021-46933 7.8 HIGH usb: gadget: f_fs: Clear ffs_eventfd in ffs_data_clear.
CVE-2021-46922 7.8 HIGH KEYS: trusted: Fix TPM reservation for seal/unseal
CVE-2021-46960 7.5 HIGH cifs: Return correct error code from smb2_get_enc_key
CVE-2021-46948 7.5 HIGH sfc: farch: fix TX queue lookup in TX event handling
CVE-2021-46974 7.1 HIGH bpf: Fix masking negation logic upon negative dst register
CVE-2021-46908 7.1 HIGH bpf: Use correct permission flag for mixed signed bounds arithmetic
CVE-2021-46910 7.0 HIGH ARM: 9063/1: mm: reduce maximum number of CPUs if DEBUG_KMAP_LOCAL is enabled
CVE-2021-46951 tpm: efi: Use local variable for calculating final log size

Showing top 20 of 67 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-46912

No comments yet

Leave a comment