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CVE-2021-4442— tcp: add sanity tests to TCP_QUEUE_SEQ

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，该漏洞源于当队列不为空时错误地应用了TCP_QUEUE_SEQ选项，导致连接被重置。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.39% · P32

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux ee9952831cfd0bbe834f4a26489d7dce74582e37< 319f460237fc2965a80aa9a055044e1da7b3692a affected
ee9952831cfd0bbe834f4a26489d7dce74582e37< 3bf899438c123c444f6b644a57784dfbb6b15ad6 affected
ee9952831cfd0bbe834f4a26489d7dce74582e37< 046f3c1c2ff450fb7ae53650e9a95e0074a61f3e affected
ee9952831cfd0bbe834f4a26489d7dce74582e37< 3b72d5a703842f582502d97906f17d6ee122dac2 affected
ee9952831cfd0bbe834f4a26489d7dce74582e37< 8811f4a9836e31c14ecdf79d9f3cb7c5d463265d affected
3.5 affected
< 3.5 unaffected
4.19.181≤ 4.19.* unaffected
… +4 more rows
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I. Basic Information for CVE-2021-4442

Vulnerability Information
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Vulnerability Title
tcp: add sanity tests to TCP_QUEUE_SEQ
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: tcp: add sanity tests to TCP_QUEUE_SEQ Qingyu Li reported a syzkaller bug where the repro changes RCV SEQ _after_ restoring data in the receive queue. mprotect(0x4aa000, 12288, PROT_READ) = 0 mmap(0x1ffff000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x1ffff000 mmap(0x20000000, 16777216, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x20000000 mmap(0x21000000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x21000000 socket(AF_INET6, SOCK_STREAM, IPPROTO_IP) = 3 setsockopt(3, SOL_TCP, TCP_REPAIR, [1], 4) = 0 connect(3, {sa_family=AF_INET6, sin6_port=htons(0), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_scope_id=0}, 28) = 0 setsockopt(3, SOL_TCP, TCP_REPAIR_QUEUE, [1], 4) = 0 sendmsg(3, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="0x0000000000000003\0\0", iov_len=20}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 20 setsockopt(3, SOL_TCP, TCP_REPAIR, [0], 4) = 0 setsockopt(3, SOL_TCP, TCP_QUEUE_SEQ, [128], 4) = 0 recvfrom(3, NULL, 20, 0, NULL, NULL) = -1 ECONNRESET (Connection reset by peer) syslog shows: [ 111.205099] TCP recvmsg seq # bug 2: copied 80, seq 0, rcvnxt 80, fl 0 [ 111.207894] WARNING: CPU: 1 PID: 356 at net/ipv4/tcp.c:2343 tcp_recvmsg_locked+0x90e/0x29a0 This should not be allowed. TCP_QUEUE_SEQ should only be used when queues are empty. This patch fixes this case, and the tx path as well.
Source: CVE Program / CVE List V5
CVSS Information
N/A
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，该漏洞源于当队列不为空时错误地应用了TCP_QUEUE_SEQ选项，导致连接被重置。
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 ee9952831cfd0bbe834f4a26489d7dce74582e37 ~ 319f460237fc2965a80aa9a055044e1da7b3692a -
Linux Linux 3.5 -

II. Public POCs for CVE-2021-4442

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III. Intelligence Information for CVE-2021-4442

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IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-4442

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