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CVE-2026-53070— sctp: disable BH before calling udp_tunnel_xmit_skb()

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基金会开源的操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于SCTP协议栈未在调用udp_tunnel_xmit_skb()前禁用BH（下半部），可能导致dev_xmit_recursion_inc()/dec()在不同CPU上不平衡，从而造成数据包丢弃。以下版本受到影响：5.11版本。

CVSS 7.5 · High EPSS 0.35% · P27

Possible ATT&CK Techniques 1 AI

T1498.002 · Reflection Amplification

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 046c052b475e7119b6a30e3483e2888fc606a2f8< be3bfcb34bda04f6a350710db471d4133f950f2c affected
046c052b475e7119b6a30e3483e2888fc606a2f8< 0de7db2eb27e82b983157016fa604b1ba664ae5f affected
046c052b475e7119b6a30e3483e2888fc606a2f8< 790093245e35040c2adb15f48970020425aa3f47 affected
046c052b475e7119b6a30e3483e2888fc606a2f8< 2cd7e6971fc2787408ceef17906ea152791448cf affected
5.11 affected
< 5.11 unaffected
6.12.95≤ 6.12.* unaffected
6.18.37≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-53070

Vulnerability Information
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Vulnerability Title
sctp: disable BH before calling udp_tunnel_xmit_skb()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: sctp: disable BH before calling udp_tunnel_xmit_skb() udp_tunnel_xmit_skb() / udp_tunnel6_xmit_skb() are expected to run with BH disabled. After commit 6f1a9140ecda ("add xmit recursion limit to tunnel xmit functions"), on the path: udp(6)_tunnel_xmit_skb() -> ip(6)tunnel_xmit() dev_xmit_recursion_inc()/dec() must stay balanced on the same CPU. Without local_bh_disable(), the context may move between CPUs, which can break the inc/dec pairing. This may lead to incorrect recursion level detection and cause packets to be dropped in ip(6)_tunnel_xmit() or __dev_queue_xmit(). Fix it by disabling BH around both IPv4 and IPv6 SCTP UDP xmit paths. In my testing, after enabling the SCTP over UDP: # ip net exec ha sysctl -w net.sctp.udp_port=9899 # ip net exec ha sysctl -w net.sctp.encap_port=9899 # ip net exec hb sysctl -w net.sctp.udp_port=9899 # ip net exec hb sysctl -w net.sctp.encap_port=9899 # ip net exec ha iperf3 -s - without this patch: # ip net exec hb iperf3 -c 192.168.0.1 --sctp [ 5] 0.00-10.00 sec 37.2 MBytes 31.2 Mbits/sec sender [ 5] 0.00-10.00 sec 37.1 MBytes 31.1 Mbits/sec receiver - with this patch: # ip net exec hb iperf3 -c 192.168.0.1 --sctp [ 5] 0.00-10.00 sec 3.14 GBytes 2.69 Gbits/sec sender [ 5] 0.00-10.00 sec 3.14 GBytes 2.69 Gbits/sec receiver
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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基金会开源的操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于SCTP协议栈未在调用udp_tunnel_xmit_skb()前禁用BH（下半部），可能导致dev_xmit_recursion_inc()/dec()在不同CPU上不平衡，从而造成数据包丢弃。以下版本受到影响：5.11版本。
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 046c052b475e7119b6a30e3483e2888fc606a2f8 ~ be3bfcb34bda04f6a350710db471d4133f950f2c -
Linux Linux 5.11 -

II. Public POCs for CVE-2026-53070

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III. Intelligence Information for CVE-2026-53070

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Patches & Fixes for CVE-2026-53070 (4)

Same Patch Batch · Linux · 2026-06-24 · 219 CVEs total

CVE-2026-53049 9.8 CRITICAL gfs2: add some missing log locking
CVE-2026-52993 9.8 CRITICAL tipc: fix double-free in tipc_buf_append()
CVE-2026-52989 9.8 CRITICAL nvmet-tcp: propagate nvmet_tcp_build_pdu_iovec() errors to its callers
CVE-2026-52986 9.8 CRITICAL netfilter: nf_conntrack_sip: don't use simple_strtoul
CVE-2026-52982 9.8 CRITICAL net: usb: rtl8150: fix use-after-free in rtl8150_start_xmit()
CVE-2026-53002 9.8 CRITICAL netfilter: conntrack: remove sprintf usage
CVE-2026-53086 9.8 CRITICAL net: bcmgenet: fix racing timeout handler
CVE-2026-53045 9.8 CRITICAL memory: tegra124-emc: Fix dll_change check
CVE-2026-53006 9.8 CRITICAL ipv6: fix possible UAF in icmpv6_rcv()
CVE-2026-53046 9.8 CRITICAL ksmbd: fix use-after-free from async crypto on Qualcomm crypto engine
CVE-2026-52955 9.8 CRITICAL libceph: Fix potential out-of-bounds access in crush_decode()
CVE-2026-53010 9.8 CRITICAL ksmbd: fix use-after-free in smb2_open during durable reconnect
CVE-2026-53088 9.8 CRITICAL net: bcmgenet: fix off-by-one in bcmgenet_put_txcb
CVE-2026-52924 9.8 CRITICAL sctp: purge outqueue on stale COOKIE-ECHO handling
CVE-2026-52931 9.8 CRITICAL batman-adv: tp_meter: avoid use of uninit sender vars
CVE-2026-53055 9.8 CRITICAL crypto: hisilicon/sec2 - prevent req used-after-free for sec
CVE-2026-52914 9.8 CRITICAL batman-adv: fix fragment reassembly length accounting
CVE-2026-52958 9.1 CRITICAL libceph: Fix potential out-of-bounds access in osdmap_decode()
CVE-2026-53043 9.1 CRITICAL ocfs2/dlm: validate qr_numregions in dlm_match_regions()
CVE-2026-52999 9.1 CRITICAL netfilter: nfnetlink_osf: fix out-of-bounds read on option matching

Showing top 20 of 219 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-53070

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