Linux Kernel up to 6.5.2 bpf some_lookup_func reference count

CVSS Meta Temp Score
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CTI Interest Score
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5.5$0-$5k0.00

Summaryinfo

A vulnerability has been found in Linux Kernel up to 5.10.194/5.15.131/6.1.52/6.4.15/6.5.2 and classified as critical. The impacted element is the function some_lookup_func of the component bpf. This manipulation causes reference count. The identification of this vulnerability is CVE-2023-53585. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 5.10.194/5.15.131/6.1.52/6.4.15/6.5.2. Affected by this vulnerability is the function some_lookup_func of the component bpf. The manipulation with an unknown input leads to a reference count vulnerability. The CWE definition for the vulnerability is CWE-911. The product uses a reference count to manage a resource, but it does not update or incorrectly updates the reference count. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: bpf: reject unhashed sockets in bpf_sk_assign The semantics for bpf_sk_assign are as follows: sk = some_lookup_func() bpf_sk_assign(skb, sk) bpf_sk_release(sk) That is, the sk is not consumed by bpf_sk_assign. The function therefore needs to make sure that sk lives long enough to be consumed from __inet_lookup_skb. The path through the stack for a TCPv4 packet is roughly: netif_receive_skb_core: takes RCU read lock __netif_receive_skb_core: sch_handle_ingress: tcf_classify: bpf_sk_assign() deliver_ptype_list_skb: deliver_skb: ip_packet_type->func == ip_rcv: ip_rcv_core: ip_rcv_finish_core: dst_input: ip_local_deliver: ip_local_deliver_finish: ip_protocol_deliver_rcu: tcp_v4_rcv: __inet_lookup_skb: skb_steal_sock The existing helper takes advantage of the fact that everything happens in the same RCU critical section: for sockets with SOCK_RCU_FREE set bpf_sk_assign never takes a reference. skb_steal_sock then checks SOCK_RCU_FREE again and does sock_put if necessary. This approach assumes that SOCK_RCU_FREE is never set on a sk between bpf_sk_assign and skb_steal_sock, but this invariant is violated by unhashed UDP sockets. A new UDP socket is created in TCP_CLOSE state but without SOCK_RCU_FREE set. That flag is only added in udp_lib_get_port() which happens when a socket is bound. When bpf_sk_assign was added it wasn't possible to access unhashed UDP sockets from BPF, so this wasn't a problem. This changed in commit 0c48eefae712 ("sock_map: Lift socket state restriction for datagram sockets"), but the helper wasn't adjusted accordingly. The following sequence of events will therefore lead to a refcount leak: 1. Add socket(AF_INET, SOCK_DGRAM) to a sockmap. 2. Pull socket out of sockmap and bpf_sk_assign it. Since SOCK_RCU_FREE is not set we increment the refcount. 3. bind() or connect() the socket, setting SOCK_RCU_FREE. 4. skb_steal_sock will now set refcounted = false due to SOCK_RCU_FREE. 5. tcp_v4_rcv() skips sock_put(). Fix the problem by rejecting unhashed sockets in bpf_sk_assign(). This matches the behaviour of __inet_lookup_skb which is ultimately the goal of bpf_sk_assign().

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2023-53585 since 10/04/2025. The exploitation appears to be easy. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 302981 (EulerOS Virtualization 2.13.1 : kernel (EulerOS-SA-2026-1637)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.195, 5.15.132, 6.1.53, 6.4.16 or 6.5.3 eliminates this vulnerability. Applying the patch 791a12102e5191dcb6ce0b3a99d71b5a2802d12a/7dcbc0bb0e5cc1823923744befce59ac353135e6/c0ce0fb76610d5fad31f56f2ca8241a2a6717a1b/8aa43cfbb68b25119d2ced14ec717173e2901fa2/3d4522f59fb748a54446846522941a4f09da63e9/67312adc96b5a585970d03b62412847afe2c6b01 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 (302981), EUVD (EUVD-2023-60023) and CERT Bund (WID-SEC-2025-2194). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Google Cloud Platform
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • Open Source Linux Kernel
  • RESF Rocky Linux
  • IBM QRadar SIEM

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.6
VulDB Meta Temp Score: 5.5

VulDB Base Score: 5.7
VulDB Temp Score: 5.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

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

Exploitinginfo

Class: Reference count
CWE: CWE-911 / CWE-664
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 302981
Nessus Name: EulerOS Virtualization 2.13.1 : kernel (EulerOS-SA-2026-1637)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.195/5.15.132/6.1.53/6.4.16/6.5.3
Patch: 791a12102e5191dcb6ce0b3a99d71b5a2802d12a/7dcbc0bb0e5cc1823923744befce59ac353135e6/c0ce0fb76610d5fad31f56f2ca8241a2a6717a1b/8aa43cfbb68b25119d2ced14ec717173e2901fa2/3d4522f59fb748a54446846522941a4f09da63e9/67312adc96b5a585970d03b62412847afe2c6b01

Timelineinfo

10/04/2025 Advisory disclosed
10/04/2025 +0 days CVE reserved
10/04/2025 +0 days VulDB entry created
03/21/2026 +168 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2023-53585 (🔒)
GCVE (CVE): GCVE-0-2023-53585
GCVE (VulDB): GCVE-100-327169
EUVD: 🔒
CERT Bund: WID-SEC-2025-2194 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 10/04/2025 20:26
Updated: 03/21/2026 12:15
Changes: 10/04/2025 20:26 (59), 10/04/2025 22:28 (1), 11/23/2025 21:39 (7), 12/26/2025 15:04 (1), 02/10/2026 14:13 (10), 03/21/2026 12:15 (2)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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