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CVE-2026-52947— net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove

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 4.7版本存在安全漏洞，该漏洞源于qrtr_port_remove函数中的引用计数饱和和潜在释放后重用问题，可能导致并发RCU读取器获取已经释放的套接字指针，导致释放后重用。以下版本受到影响：4.7版本。

CVSS 7.8 · High EPSS 0.14% · P3

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux bdabad3e363d825ddf9679dd431cca0b2c30f881< 2aa4c12723fe432e623462a3be42a197a128722b affected
bdabad3e363d825ddf9679dd431cca0b2c30f881< 03bfa95e452e2b6ccd76a332060ae4feaf5ad84d affected
bdabad3e363d825ddf9679dd431cca0b2c30f881< 474293d90880622fde9d2430fb0165767090f7b3 affected
bdabad3e363d825ddf9679dd431cca0b2c30f881< 2047c2aa0963bb2872fd722300a15bcb441a4c00 affected
bdabad3e363d825ddf9679dd431cca0b2c30f881< 7de2d447072be3b1a76793f034432338fc9c494b affected
bdabad3e363d825ddf9679dd431cca0b2c30f881< ab269990ed58143a92a263be1bee626d82ac03da affected
bdabad3e363d825ddf9679dd431cca0b2c30f881< 3b20ec8f31e8a6a6782243f473b0abd3463621df affected
bdabad3e363d825ddf9679dd431cca0b2c30f881< a2171131ecda1ed61a594a1eb715e75fdad0fef5 affected
… +10 more rows
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I. Basic Information for CVE-2026-52947

Vulnerability Information
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Vulnerability Title
net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove In qrtr_port_remove(), the socket reference count is decremented via __sock_put() before the port is removed from the qrtr_ports XArray and before the RCU grace period elapses. This breaks the fundamental RCU update paradigm. It exposes a race window where a concurrent RCU reader (such as qrtr_reset_ports() or qrtr_port_lookup()) can obtain a pointer to the socket from the XArray, and attempt to call sock_hold() on a socket whose reference count has already dropped to zero. This exact race condition was hit during syzkaller fuzzing, leading to the following refcount saturation warning and a potential Use-After-Free: refcount_t: saturated; leaking memory. WARNING: CPU: 3 PID: 1273 at lib/refcount.c:22 refcount_warn_saturate+0xae/0x1d0 Modules linked in: qrtr(+) bochs drm_shmem_helper ... Call Trace: <TASK> qrtr_reset_ports net/qrtr/af_qrtr.c:768 [inline] [qrtr] __qrtr_bind.isra.0+0x48b/0x570 net/qrtr/af_qrtr.c:805 [qrtr] qrtr_bind+0x17d/0x210 net/qrtr/af_qrtr.c:901 [qrtr] kernel_bind+0xe4/0x120 net/socket.c:3592 qrtr_ns_init+0x1a6/0x380 net/qrtr/ns.c:715 [qrtr] qrtr_proto_init+0x3b/0xff0 net/qrtr/af_qrtr.c:169 [qrtr] do_one_initcall+0xf5/0x5e0 init/main.c:1283 ... </TASK> Fix this by deferring the reference count decrement until after the xa_erase() and the synchronize_rcu() complete. (Note: The v1 of this patch incorrectly replaced __sock_put() with sock_put(). As Simon Horman pointed out, the callers of qrtr_port_remove() still hold a reference to the socket, so freeing the socket memory here would lead to a subsequent UAF in the caller. Thus, the __sock_put() is kept, but only repositioned to close the RCU race.)
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 4.7版本存在安全漏洞，该漏洞源于qrtr_port_remove函数中的引用计数饱和和潜在释放后重用问题，可能导致并发RCU读取器获取已经释放的套接字指针，导致释放后重用。以下版本受到影响：4.7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 bdabad3e363d825ddf9679dd431cca0b2c30f881 ~ 2aa4c12723fe432e623462a3be42a197a128722b -
Linux Linux 4.7 -

II. Public POCs for CVE-2026-52947

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III. Intelligence Information for CVE-2026-52947

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Patches & Fixes for CVE-2026-52947 (8)

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

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

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-2026-52947

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