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CVE-2026-53264— net/sched: act_api: use RCU with deferred freeing for action lifecycle

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net/sched/act_api中NEWTFILTER与DELFILTER并发运行时存在竞争条件，可能导致释放后重用。

CVSS 7.8 · High EPSS 0.25% · P15

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da< 98b2e40879abf0245be5a5b7af69e0f6ff524ac3 affected
d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da< 18af5d2ef0c4f65787fd1280c8b23286b9f2a835 affected
d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da< 1f1b98fea6b9ea30507d0f2fbff6750292d097e2 affected
d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da< 8b136f18ac4b2ace5aaad3305b3f8a5d8165a009 affected
d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da< 5dd51e09020c65aa53cf128e5e3517cd53b3c113 affected
d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da< b60e9391142e983fab2be53497aa8f71fdd09cd5 affected
d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da< 91d105d2cbe002f9c7b43a6183adedc37e1da1f7 affected
d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da< 5057e1aca011e51ef51498c940ef96f3d3e8a305 affected
… +10 more rows
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I. Basic Information for CVE-2026-53264

Vulnerability Information
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Vulnerability Title
net/sched: act_api: use RCU with deferred freeing for action lifecycle
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_api: use RCU with deferred freeing for action lifecycle When NEWTFILTER and DELFILTER are run concurrently it is possible to create a race with an associated action. Let's illustrate with CPU0 running NEWTFILTER and CPU1 running DELFILTER: 0: mutex_lock() <-- holds the idr lock 0: rcu_read_lock() 0: p = idr_find(idr, index) <-- action p is valid (RCU protects IDR) 0: mutex_unlock() <-- releases the idr lock 1: refcount_dec_and_mutex_lock() <-- refcnt 1->0, mutex held 1: idr_remove(idr, index) <-- Action removed from IDR 1: mutex_unlock() <-- mutex released allowing us to delete the action 1: tcf_action_cleanup(p); kfree(p) <-- Kfrees p immediately, no deferral 0: refcount_inc_not_zero(&p->tcfa_refcnt) <-- ouch, UAF p points to freed memory This patch fixes the race condition between NEWTFILTER and DELFILTER by adding struct rcu_head to tc_action used in the deferral and introducing a call_rcu() in the delete path to defer the final kfree(). Note: this is a revert of commit d7fb60b9cafb ("net_sched: get rid of tcfa_rcu") but also modernization/simplification to directly use kfree_rcu(). Let's illustrate the new restored code path: 0: rcu_read_lock() 1: refcount_dec_and_mutex_lock() <-- refcnt 1->0, mutex held 1: idr_remove(idr, index) 1: mutex_unlock() 1: call_rcu(&p->tcfa_rcu, tcf_action_rcu_free) <-- defer kfree after grace period 0: p = idr_find(idr, index) 0: refcount_inc_not_zero(&p->tcfa_refcnt) <-- fails, refcnt already 0 1: rcu_read_unlock() <-- release so freeing can run after grace period After CPU1 calls idr_remove(), the object is no longer reachable through the IDR. CPU0's subsequent idr_find() will return NULL, and even if it still held a stale pointer, the immediate kfree() is now deferred until after the RCU grace period, so no UAF can occur.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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net/sched/act_api中NEWTFILTER与DELFILTER并发运行时存在竞争条件，可能导致释放后重用。
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 d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da ~ 98b2e40879abf0245be5a5b7af69e0f6ff524ac3 -
Linux Linux 4.14 -

II. Public POCs for CVE-2026-53264

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III. Intelligence Information for CVE-2026-53264

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Patches & Fixes for CVE-2026-53264 (8)

Same Patch Batch · Linux · 2026-06-25 · 146 CVEs total

CVE-2026-53175 9.8 CRITICAL inet: frags: fix use-after-free caused by the fqdir_pre_exit() flush
CVE-2026-53176 9.8 CRITICAL IB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN
CVE-2026-53228 9.8 CRITICAL ipv6: sit: reload inner IPv6 header after GSO offloads
CVE-2026-53221 9.8 CRITICAL ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()
CVE-2026-53246 9.8 CRITICAL sctp: validate cached peer INIT chunk length in COOKIE_ECHO processing
CVE-2026-53247 9.8 CRITICAL net: ethernet: mtk_eth_soc: Fix use-after-free in metadata dst teardown
CVE-2026-53151 9.8 CRITICAL rxrpc: Fix the ACK parser to extract the SACK table for parsing
CVE-2026-53216 9.8 CRITICAL net: mvpp2: limit XDP frame size to the RX buffer
CVE-2026-53260 9.8 CRITICAL tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req().
CVE-2026-53215 9.8 CRITICAL net: mvpp2: refill RX buffers before XDP or skb use
CVE-2026-53131 9.4 CRITICAL netfilter: require Ethernet MAC header before using eth_hdr()
CVE-2026-53225 9.1 CRITICAL sctp: fix uninit-value in __sctp_rcv_asconf_lookup()
CVE-2026-53224 9.1 CRITICAL sctp: validate embedded INIT chunk and address list lengths in cookie
CVE-2026-53186 9.1 CRITICAL RDMA/srp: bound SRP_RSP sense copy by the received length
CVE-2026-53159 8.8 HIGH misc: fastrpc: fix DMA address corruption due to find_vma misuse
CVE-2026-53198 8.8 HIGH ksmbd: fix use-after-free of a deferred file_lock on double SMB2_CANCEL
CVE-2026-53240 8.8 HIGH xfrm: iptfs: fix use-after-free on first_skb in __input_process_payload
CVE-2026-53275 8.8 HIGH ipv6: mcast: Fix use-after-free when processing MLD queries
CVE-2026-53188 8.8 HIGH RDMA/core: Validate the passed in fops for ib_get_ucaps()
CVE-2026-53171 8.8 HIGH accel/ethosu: fix arithmetic issues in dma_length()

Showing top 20 of 146 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-53264

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