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CVE-2026-74740— net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain

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.

在 Linux 内核中，以下漏洞已得到修复： net/sched: act_api: 修复 a->goto_chain 上的 TOCTOU 空指针解引用问题 在处理 时，首先通过 检查 ，随后调用 。而后者会执行第二次、独立的 读取，并立即解引用 。若在此期间并发执行 （例如 gact 替换路径），可能在两次读取之间将 置空，导致第二次读取返回 NULL，进而使 发生 NULL 指针解引用错误。 修复方案： 通过消除“检查后使用”（TOCTOU）竞态条件，在 中仅执行一次 读取 ，对该值进行一次 NULL 检查，并

AI Predicted 7.5 Difficulty: Hard EPSS 0.18% · P7

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5< 91d55fd1fdb85c8371ca8793c788ea7d5192383a affected
ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5< 1ec48b6715c29b20105e3485206602cff6c51ae5 affected
ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5< abceabc4408fca6a9dd52611f5d197dec9390d63 affected
ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5< 6b70886ebc428eed43a069c8944a931b5fb3f4e4 affected
ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5< f60b396ee174206fe08ebf997d16cd3801b77b22 affected
5.1 affected
< 5.1 unaffected
6.6.153≤ 6.6.* unaffected
… +4 more rows
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I. Basic Information for CVE-2026-74740

Vulnerability Information
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Vulnerability Title
net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain tcf_action_exec() handles TC_ACT_GOTO_CHAIN by first checking rcu_access_pointer(a->goto_chain) and then calling tcf_action_goto_chain_exec(), which does a second, independent rcu_dereference_bh(a->goto_chain) read and immediately dereferences chain->filter_chain. A concurrent tcf_action_set_ctrlact() (e.g. the gact replace path) can clear a->goto_chain between the two reads, so the second read returns NULL and tcf_action_goto_chain_exec() dereferences NULL. Fix the race by doing a single rcu_dereference_bh() read of a->goto_chain in tcf_action_exec(), checking it once for NULL, and passing the resulting chain pointer into tcf_action_goto_chain_exec(). This turns the split check/use into a single check/use on one value.
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

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 ~ 91d55fd1fdb85c8371ca8793c788ea7d5192383a -
Linux Linux 5.1 -

II. Public POCs for CVE-2026-74740

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III. Intelligence Information for CVE-2026-74740

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Patches & Fixes for CVE-2026-74740 (5)

Same Patch Batch · Linux · 2026-08-26 · 92 CVEs total

CVE-2026-80558 9.8 CRITICAL libceph: Avoid using invalid osd indices from primary_temp
CVE-2026-80587 9.8 CRITICAL mptcp: avoid combining some incoming suboptions
CVE-2026-74752 9.8 CRITICAL sctp: validate cookie AUTH state before use
CVE-2026-74746 9.8 CRITICAL netfilter: flowtable: publish GC-visible tuple last
CVE-2026-80519 9.8 CRITICAL ovpn: finish crypto callback cleanup before peer release
CVE-2026-74744 9.8 CRITICAL ipvlan: inherit needed_headroom and needed_tailroom from phy_dev
CVE-2026-74743 9.8 CRITICAL macvlan: inherit needed_headroom and needed_tailroom from lowerdev
CVE-2026-80557 9.8 CRITICAL libceph: fix OOB read in decode_watchers() via missing bounds check
CVE-2026-80586 9.8 CRITICAL mptcp: options: reset DSS fields in case of unexpected size
CVE-2026-80561 9.8 CRITICAL libceph: fix multiple unsafe decodes in decode_locker()
CVE-2026-74737 9.8 CRITICAL net: ethernet: ti: am65-cpsw-nuss: Fix port_id extraction from SRC TAG
CVE-2026-80589 9.8 CRITICAL block: stop the timeout timer when releasing a never added disk
CVE-2026-80528 9.8 CRITICAL ceph: avoid fs reclaim while using current->journal_info
CVE-2026-80585 9.4 CRITICAL mptcp: fastopen: only mark MPTFO subflows with SYN data
CVE-2026-74751 9.4 CRITICAL riscv: lib: Fix ZBB strnlen reading past count boundary
CVE-2026-80554 9.3 CRITICAL s390/vfio_ccw: Limit the number of channel program segments
CVE-2026-80551 9.3 CRITICAL s390/vfio_ccw: Ensure first IDAW remains constant
CVE-2026-80576 8.8 HIGH drm/amdgpu: reject oversized IBs with per-ring packet limits
CVE-2026-80547 8.8 HIGH s390/vfio_ccw: Implement a crw lock
CVE-2026-80548 8.8 HIGH s390/vfio_ccw: Selectively expand io_mutex

Showing top 20 of 92 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-74740

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