Linux Kernel up to 6.3.1 memory leak

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5.0	$0-$5k	0.00

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 6.3.1. This affects an unknown function. Performing a manipulation results in memory leak. This vulnerability is identified as CVE-2023-53489. The attack is only possible with local access. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.3.1. This affects an unknown code. The manipulation with an unknown input leads to a memory leak vulnerability. CWE is classifying the issue as CWE-401. The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. This is going to have an impact on availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: tcp/udp: Fix memleaks of sk and zerocopy skbs with TX timestamp. syzkaller reported [0] memory leaks of an UDP socket and ZEROCOPY skbs. We can reproduce the problem with these sequences: sk = socket(AF_INET, SOCK_DGRAM, 0) sk.setsockopt(SOL_SOCKET, SO_TIMESTAMPING, SOF_TIMESTAMPING_TX_SOFTWARE) sk.setsockopt(SOL_SOCKET, SO_ZEROCOPY, 1) sk.sendto(b'', MSG_ZEROCOPY, ('127.0.0.1', 53)) sk.close() sendmsg() calls msg_zerocopy_alloc(), which allocates a skb, sets skb->cb->ubuf.refcnt to 1, and calls sock_hold(). Here, struct ubuf_info_msgzc indirectly holds a refcnt of the socket. When the skb is sent, __skb_tstamp_tx() clones it and puts the clone into the socket's error queue with the TX timestamp. When the original skb is received locally, skb_copy_ubufs() calls skb_unclone(), and pskb_expand_head() increments skb->cb->ubuf.refcnt. This additional count is decremented while freeing the skb, but struct ubuf_info_msgzc still has a refcnt, so __msg_zerocopy_callback() is not called. The last refcnt is not released unless we retrieve the TX timestamped skb by recvmsg(). Since we clear the error queue in inet_sock_destruct() after the socket's refcnt reaches 0, there is a circular dependency. If we close() the socket holding such skbs, we never call sock_put() and leak the count, sk, and skb. TCP has the same problem, and commit e0c8bccd40fc ("net: stream: purge sk_error_queue in sk_stream_kill_queues()") tried to fix it by calling skb_queue_purge() during close(). However, there is a small chance that skb queued in a qdisc or device could be put into the error queue after the skb_queue_purge() call. In __skb_tstamp_tx(), the cloned skb should not have a reference to the ubuf to remove the circular dependency, but skb_clone() does not call skb_copy_ubufs() for zerocopy skb. So, we need to call skb_orphan_frags_rx() for the cloned skb to call skb_copy_ubufs(). [0]: BUG: memory leak unreferenced object 0xffff88800c6d2d00 (size 1152): comm "syz-executor392", pid 264, jiffies 4294785440 (age 13.044s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 cd af e8 81 00 00 00 00 ................ 02 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............ backtrace: [<0000000055636812>] sk_prot_alloc+0x64/0x2a0 net/core/sock.c:2024 [<0000000054d77b7a>] sk_alloc+0x3b/0x800 net/core/sock.c:2083 [<0000000066f3c7e0>] inet_create net/ipv4/af_inet.c:319 [inline] [<0000000066f3c7e0>] inet_create+0x31e/0xe40 net/ipv4/af_inet.c:245 [<000000009b83af97>] __sock_create+0x2ab/0x550 net/socket.c:1515 [<00000000b9b11231>] sock_create net/socket.c:1566 [inline] [<00000000b9b11231>] __sys_socket_create net/socket.c:1603 [inline] [<00000000b9b11231>] __sys_socket_create net/socket.c:1588 [inline] [<00000000b9b11231>] __sys_socket+0x138/0x250 net/socket.c:1636 [<000000004fb45142>] __do_sys_socket net/socket.c:1649 [inline] [<000000004fb45142>] __se_sys_socket net/socket.c:1647 [inline] [<000000004fb45142>] __x64_sys_socket+0x73/0xb0 net/socket.c:1647 [<0000000066999e0e>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<0000000066999e0e>] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80 [<0000000017f238c1>] entry_SYSCALL_64_after_hwframe+0x63/0xcd BUG: memory leak unreferenced object 0xffff888017633a00 (size 240): comm "syz-executor392", pid 264, jiffies 4294785440 (age 13.044s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 2d 6d 0c 80 88 ff ff .........-m..... backtrace: [<000000002b1c4368>] __alloc_skb+0x229/0x320 net/core/skbuff.c:497 [<00000000143579a6>] alloc_skb include/linux/skbuff.h:1265 [inline] [<00000000143579a6>] sock_omalloc+0xaa/0x190 net/core/sock.c:2596 [<00000000be626478>] msg_zerocopy_alloc net/core/skbuff.c:1294 [inline] [<00000000be626478>] ---truncated---

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2023-53489 since 10/01/2025. The exploitability is told to be difficult. Attacking locally is a requirement. The technical details are unknown and an exploit is not publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 269617 (Linux Distros Unpatched Vulnerability : CVE-2023-53489), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.14.315, 4.19.283, 5.4.243, 5.10.180, 5.15.111, 6.1.28, 6.2.15 or 6.3.2 eliminates this vulnerability. Applying the patch 281072fb2a7294cde7acbf5375b879f40a8001b7/1f69c086b20e27763af28145981435423f088268/602fa8af44fd55a58f9e94eb673e8adad2c6cc46/230a5ed7d813fb516de81d23f09d7506753e41e9/43e4197dd5f6b474a8b16f8b6a42cd45cf4f9d1a/cb52e7f24c1d01a536a847dff0d1d95889cc3b5c/30290f210ba7426ff7592fe2eb4114b1b5bad219/426384dd4980040651536fef5feac4dcc4d7ee4e/50749f2dd6854a41830996ad302aef2ffaf011d8 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (269617), EUVD (EUVD-2025-32784) and CERT Bund (WID-SEC-2025-2187). Be aware that VulDB is the high quality source for vulnerability data.

Affected

• Amazon Linux 2
• Red Hat Enterprise Linux
• SUSE Linux
• Oracle Linux
• Open Source Linux Kernel
• Dell Secure Connect Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 4.14.314
• 4.19.282
• 5.4.242
• 5.10.179
• 5.15.110
• 6.1.0
• 6.1.1
• 6.1.2
• 6.1.3
• 6.1.4
• 6.1.5
• 6.1.6
• 6.1.7
• 6.1.8
• 6.1.9
• 6.1.10
• 6.1.11
• 6.1.12
• 6.1.13
• 6.1.14
• 6.1.15
• 6.1.16
• 6.1.17
• 6.1.18
• 6.1.19
• 6.1.20
• 6.1.21
• 6.1.22
• 6.1.23
• 6.1.24
• 6.1.25
• 6.1.26
• 6.1.27
• 6.2.0
• 6.2.1
• 6.2.2
• 6.2.3
• 6.2.4
• 6.2.5
• 6.2.6
• 6.2.7
• 6.2.8
• 6.2.9
• 6.2.10
• 6.2.11
• 6.2.12
• 6.2.13
• 6.2.14
• 6.3.0
• 6.3.1

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
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CPE 2.2info

• 🔒
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CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.1
VulDB Meta Temp Score: 5.0

VulDB Base Score: 4.7
VulDB Temp Score: 4.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Memory leak
CWE: CWE-401 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 269617
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2023-53489

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 4.14.315/4.19.283/5.4.243/5.10.180/5.15.111/6.1.28/6.2.15/6.3.2
Patch: 281072fb2a7294cde7acbf5375b879f40a8001b7/1f69c086b20e27763af28145981435423f088268/602fa8af44fd55a58f9e94eb673e8adad2c6cc46/230a5ed7d813fb516de81d23f09d7506753e41e9/43e4197dd5f6b474a8b16f8b6a42cd45cf4f9d1a/cb52e7f24c1d01a536a847dff0d1d95889cc3b5c/30290f210ba7426ff7592fe2eb4114b1b5bad219/426384dd4980040651536fef5feac4dcc4d7ee4e/50749f2dd6854a41830996ad302aef2ffaf011d8

Timelineinfo

10/01/2025 Advisory disclosed
10/01/2025 +0 days CVE reserved
10/01/2025 +0 days VulDB entry created
01/22/2026 +113 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2023-53489 (🔒)
GCVE (CVE): GCVE-0-2023-53489
GCVE (VulDB): GCVE-100-326631
EUVD: 🔒
CERT Bund: WID-SEC-2025-2187 - Linux Kernel: Mehrere Schwachstellen erm&ouml;glichen Denial of Service

Entryinfo

Created: 10/01/2025 15:25
Updated: 01/22/2026 08:24
Changes: 10/01/2025 15:25 (57), 10/12/2025 01:08 (2), 11/28/2025 22:06 (7), 01/22/2026 01:19 (12), 01/22/2026 08:24 (1)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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