cbcvebase.
CVE-2026-46319
published 2026-06-09

CVE-2026-46319: In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: Only release RCU read lock after ct_ft When looking up a flow table in…

PriorityP340high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.13%
2.6th percentile
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: Only release RCU read lock after ct_ft When looking up a flow table in act_ct in tcf_ct_flow_table_get(), rhashtable_lookup_fast() internally opens and closes an RCU read critical section before returning ct_ft. The tcf_ct_flow_table_cleanup_work() can complete before refcount_inc_not_zero() is invoked on the returned ct_ft resulting in a UAF on the already freed ct_ft object. This vulnerability can lead to privilege escalation. Analysis from [email protected]: When initializing act_ct, tcf_ct_init() is called, which internally triggers tcf_ct_flow_table_get(). static int tcf_ct_flow_table_get(struct net *net, struct tcf_ct_params *params) { struct zones_ht_key key = { .net = net, .zone = params->zone }; struct tcf_ct_flow_table *ct_ft; int err = -ENOMEM; mutex_lock(&zones_mutex); ct_ft = rhashtable_lookup_fast(&zones_ht, &key, zones_params); // [1] if (ct_ft && refcount_inc_not_zero(&ct_ft->ref)) // [2] goto out_unlock; ... } static __always_inline void *rhashtable_lookup_fast( struct rhashtable *ht, const void *key, const struct rhashtable_params params) { void *obj; rcu_read_lock(); obj = rhashtable_lookup(ht, key, params); rcu_read_unlock(); return obj; } At [1], rhashtable_lookup_fast() looks up and returns the corresponding ct_ft from zones_ht . The lookup is performed within an RCU read critical section through rcu_read_lock() / rcu_read_unlock(), which prevents the object from being freed. However, at the point of function return, rcu_read_unlock() has already been called, and there is nothing preventing ct_ft from being freed before reaching refcount_inc_not_zero(&ct_ft->ref) at [2]. This interval becomes the race window, during which ct_ft can be freed. Free Process: tcf_ct_flow_table_put() is executed through the path tcf_ct_cleanup() call_rcu() tcf_ct_params_free_rcu() tcf_ct_params_free() tcf_ct_flow_table_put(). static void tcf_ct_flow_table

Affected

57 ranges· showing 25
VendorProductVersion rangeFixed in
linuxlinux
linuxlinux>= 138470a9b2cc2e26e6018300394afc3858a54e6a < ece578ca61e572df96cfc80456357ebfae0b4b9eece578ca61e572df96cfc80456357ebfae0b4b9e
linuxlinux>= 138470a9b2cc2e26e6018300394afc3858a54e6a < a2e0c045c87aa252eb61412e67dd91f2c2b19f81a2e0c045c87aa252eb61412e67dd91f2c2b19f81
linuxlinux>= 138470a9b2cc2e26e6018300394afc3858a54e6a < 67c9ecc9f2575273ed1323e312881fc98ac83d6d67c9ecc9f2575273ed1323e312881fc98ac83d6d
linuxlinux>= 138470a9b2cc2e26e6018300394afc3858a54e6a < f23424a0ddadb494d4bd57056a7ca703312d3a7bf23424a0ddadb494d4bd57056a7ca703312d3a7b
linuxlinux>= 138470a9b2cc2e26e6018300394afc3858a54e6a < 17dfb67cb399b660105d9a8c6100851c0d0cdc7017dfb67cb399b660105d9a8c6100851c0d0cdc70
linuxlinux>= 138470a9b2cc2e26e6018300394afc3858a54e6a < 4c727c6967a41b37efe0f26332ca9ec5b74785a34c727c6967a41b37efe0f26332ca9ec5b74785a3
linuxlinux>= 138470a9b2cc2e26e6018300394afc3858a54e6a < 3e20e1b3058e0b94638e7b931c138e840e2667243e20e1b3058e0b94638e7b931c138e840e266724
linuxlinux>= 138470a9b2cc2e26e6018300394afc3858a54e6a < f462dca0c8415bf0058d0ffa476354c4476d0f09f462dca0c8415bf0058d0ffa476354c4476d0f09
linuxlinux_kernel
linuxlinux_kernel>= 5.11 < 5.15.2095.15.209
linuxlinux_kernel>= 5.16 < 6.1.1756.1.175
linuxlinux_kernel>= 5.7 < 5.10.2585.10.258
linuxlinux_kernel>= 6.13 < 6.18.336.18.33
linuxlinux_kernel>= 6.19 < 7.0.107.0.10
linuxlinux_kernel>= 6.2 < 6.6.1416.6.141
linuxlinux_kernel>= 6.7 < 6.12.916.12.91
ubuntulinux
ubuntulinux-aws
ubuntulinux-aws-5.15
ubuntulinux-aws-fips
ubuntulinux-azure
ubuntulinux-azure-5.15
ubuntulinux-azure-6.8
ubuntulinux-azure-fde

CVSS provenance

nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_ubuntu7.1HIGH
vendor_redhat7.0HIGH
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