Vulnerability-Lookup

CVE-2023-53585 (GCVE-0-2023-53585)

Vulnerability from cvelistv5 – Published: 2025-10-04 15:44 – Updated: 2026-05-11 19:47

Title

bpf: reject unhashed sockets in bpf_sk_assign

Summary

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().

Severity

5.5 (Medium)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Assigner

Linux mitre root

References

6 references

URL	Tags
https://git.kernel.org/stable/c/791a12102e5191dcb…
https://git.kernel.org/stable/c/7dcbc0bb0e5cc1823…
https://git.kernel.org/stable/c/c0ce0fb76610d5fad…
https://git.kernel.org/stable/c/8aa43cfbb68b25119…
https://git.kernel.org/stable/c/3d4522f59fb748a54…
https://git.kernel.org/stable/c/67312adc96b5a5859…

Impacted products

2 products

Vendor	Product	Version	CPE status
Linux	Linux	Affected: cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 , < 791a12102e5191dcb6ce0b3a99d71b5a2802d12a (git) Affected: cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 , < 7dcbc0bb0e5cc1823923744befce59ac353135e6 (git) Affected: cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 , < c0ce0fb76610d5fad31f56f2ca8241a2a6717a1b (git) Affected: cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 , < 8aa43cfbb68b25119d2ced14ec717173e2901fa2 (git) Affected: cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 , < 3d4522f59fb748a54446846522941a4f09da63e9 (git) Affected: cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 , < 67312adc96b5a585970d03b62412847afe2c6b01 (git)	guessed
Linux	Linux	Affected: 5.7 Unaffected: 0 , < 5.7 (semver) Unaffected: 5.10.195 , ≤ 5.10.* (semver) Unaffected: 5.15.132 , ≤ 5.15.* (semver) Unaffected: 6.1.53 , ≤ 6.1.* (semver) Unaffected: 6.4.16 , ≤ 6.4.* (semver) Unaffected: 6.5.3 , ≤ 6.5.* (semver) Unaffected: 6.6 , ≤ * (original_commit_for_fix)	guessed

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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: reject unhashed sockets in bpf_sk_assign\n\nThe semantics for bpf_sk_assign are as follows:\n\n    sk = some_lookup_func()\n    bpf_sk_assign(skb, sk)\n    bpf_sk_release(sk)\n\nThat is, the sk is not consumed by bpf_sk_assign. The function\ntherefore needs to make sure that sk lives long enough to be\nconsumed from __inet_lookup_skb. The path through the stack for a\nTCPv4 packet is roughly:\n\n  netif_receive_skb_core: takes RCU read lock\n    __netif_receive_skb_core:\n      sch_handle_ingress:\n        tcf_classify:\n          bpf_sk_assign()\n      deliver_ptype_list_skb:\n        deliver_skb:\n          ip_packet_type-\u003efunc == ip_rcv:\n            ip_rcv_core:\n            ip_rcv_finish_core:\n              dst_input:\n                ip_local_deliver:\n                  ip_local_deliver_finish:\n                    ip_protocol_deliver_rcu:\n                      tcp_v4_rcv:\n                        __inet_lookup_skb:\n                          skb_steal_sock\n\nThe existing helper takes advantage of the fact that everything\nhappens in the same RCU critical section: for sockets with\nSOCK_RCU_FREE set bpf_sk_assign never takes a reference.\nskb_steal_sock then checks SOCK_RCU_FREE again and does sock_put\nif necessary.\n\nThis approach assumes that SOCK_RCU_FREE is never set on a sk\nbetween bpf_sk_assign and skb_steal_sock, but this invariant is\nviolated by unhashed UDP sockets. A new UDP socket is created\nin TCP_CLOSE state but without SOCK_RCU_FREE set. That flag is only\nadded in udp_lib_get_port() which happens when a socket is bound.\n\nWhen bpf_sk_assign was added it wasn\u0027t possible to access unhashed\nUDP sockets from BPF, so this wasn\u0027t a problem. This changed\nin commit 0c48eefae712 (\"sock_map: Lift socket state restriction\nfor datagram sockets\"), but the helper wasn\u0027t adjusted accordingly.\nThe following sequence of events will therefore lead to a refcount\nleak:\n\n1. Add socket(AF_INET, SOCK_DGRAM) to a sockmap.\n2. Pull socket out of sockmap and bpf_sk_assign it. Since\n   SOCK_RCU_FREE is not set we increment the refcount.\n3. bind() or connect() the socket, setting SOCK_RCU_FREE.\n4. skb_steal_sock will now set refcounted = false due to\n   SOCK_RCU_FREE.\n5. tcp_v4_rcv() skips sock_put().\n\nFix the problem by rejecting unhashed sockets in bpf_sk_assign().\nThis matches the behaviour of __inet_lookup_skb which is ultimately\nthe goal of bpf_sk_assign()."
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    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-06-30T10:30:57+00:00",
      "cve": "CVE-2023-53585",
      "id": "CVE-2023-53585",
      "initial_release_date": "2023-01-01T00:00:00+00:00",
      "product_status:fixed": "399",
      "product_status:known_affected": "52",
      "product_status:known_not_affected": "104",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bpf: reject unhashed sockets in bpf_sk_assign",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2023/cve-2023-53585.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "low",
      "current_release_date": "2026-09-02T01:43:13Z",
      "cve": "CVE-2023-53585",
      "id": "CVE-2023-53585",
      "initial_release_date": "2025-10-05T02:55:56Z",
      "product_status:known_affected": "565",
      "product_status:known_not_affected": "222",
      "product_status:recommended": "359",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2023-53585",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2023-53585.json",
      "version": "44"
    }
  }
}

GHSA-39WR-CRM4-GXMV

Vulnerability from github – Published: 2025-10-04 18:31 – Updated: 2026-02-10 15:30

Details

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:

Add socket(AF_INET, SOCK_DGRAM) to a sockmap.
Pull socket out of sockmap and bpf_sk_assign it. Since SOCK_RCU_FREE is not set we increment the refcount.
bind() or connect() the socket, setting SOCK_RCU_FREE.
skb_steal_sock will now set refcounted = false due to SOCK_RCU_FREE.
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().

Severity

5.5 (Medium)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Show details on source website

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{
  "affected": [],
  "aliases": [
    "CVE-2023-53585"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-10-04T16:15:54Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: reject unhashed sockets in bpf_sk_assign\n\nThe semantics for bpf_sk_assign are as follows:\n\n    sk = some_lookup_func()\n    bpf_sk_assign(skb, sk)\n    bpf_sk_release(sk)\n\nThat is, the sk is not consumed by bpf_sk_assign. The function\ntherefore needs to make sure that sk lives long enough to be\nconsumed from __inet_lookup_skb. The path through the stack for a\nTCPv4 packet is roughly:\n\n  netif_receive_skb_core: takes RCU read lock\n    __netif_receive_skb_core:\n      sch_handle_ingress:\n        tcf_classify:\n          bpf_sk_assign()\n      deliver_ptype_list_skb:\n        deliver_skb:\n          ip_packet_type-\u003efunc == ip_rcv:\n            ip_rcv_core:\n            ip_rcv_finish_core:\n              dst_input:\n                ip_local_deliver:\n                  ip_local_deliver_finish:\n                    ip_protocol_deliver_rcu:\n                      tcp_v4_rcv:\n                        __inet_lookup_skb:\n                          skb_steal_sock\n\nThe existing helper takes advantage of the fact that everything\nhappens in the same RCU critical section: for sockets with\nSOCK_RCU_FREE set bpf_sk_assign never takes a reference.\nskb_steal_sock then checks SOCK_RCU_FREE again and does sock_put\nif necessary.\n\nThis approach assumes that SOCK_RCU_FREE is never set on a sk\nbetween bpf_sk_assign and skb_steal_sock, but this invariant is\nviolated by unhashed UDP sockets. A new UDP socket is created\nin TCP_CLOSE state but without SOCK_RCU_FREE set. That flag is only\nadded in udp_lib_get_port() which happens when a socket is bound.\n\nWhen bpf_sk_assign was added it wasn\u0027t possible to access unhashed\nUDP sockets from BPF, so this wasn\u0027t a problem. This changed\nin commit 0c48eefae712 (\"sock_map: Lift socket state restriction\nfor datagram sockets\"), but the helper wasn\u0027t adjusted accordingly.\nThe following sequence of events will therefore lead to a refcount\nleak:\n\n1. Add socket(AF_INET, SOCK_DGRAM) to a sockmap.\n2. Pull socket out of sockmap and bpf_sk_assign it. Since\n   SOCK_RCU_FREE is not set we increment the refcount.\n3. bind() or connect() the socket, setting SOCK_RCU_FREE.\n4. skb_steal_sock will now set refcounted = false due to\n   SOCK_RCU_FREE.\n5. tcp_v4_rcv() skips sock_put().\n\nFix the problem by rejecting unhashed sockets in bpf_sk_assign().\nThis matches the behaviour of __inet_lookup_skb which is ultimately\nthe goal of bpf_sk_assign().",
  "id": "GHSA-39wr-crm4-gxmv",
  "modified": "2026-02-10T15:30:21Z",
  "published": "2025-10-04T18:31:15Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-53585"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3d4522f59fb748a54446846522941a4f09da63e9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/67312adc96b5a585970d03b62412847afe2c6b01"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/791a12102e5191dcb6ce0b3a99d71b5a2802d12a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7dcbc0bb0e5cc1823923744befce59ac353135e6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8aa43cfbb68b25119d2ced14ec717173e2901fa2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c0ce0fb76610d5fad31f56f2ca8241a2a6717a1b"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

RHSA-2020:4431

Vulnerability from csaf_redhat - Published: 2020-11-04 00:53 - Updated: 2026-08-07 02:37

Summary

Red Hat Security Advisory: kernel security, bug fix, and enhancement update

Severity

Moderate

Scope

51 vulnerabilities in this advisory, including CVE-2023-53585.

CVE-2023-53585

A reference counting flaw was found in the Linux kernel's BPF socket assignment helper when handling unhashed UDP sockets. When a BPF program assigns an unhashed UDP socket to a packet, the function increments the socket reference count assuming SOCK_RCU_FREE isn't set. However, subsequent bind or connect operations set this flag, causing the packet receive path to skip the reference decrement. This creates a permanent reference leak that prevents socket cleanup, leading to resource exhaustion and denial of service.

5.5 (Medium)


                
                  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Fixed: 120 products

https://access.redhat.com/errata/RHSA-2020:4431

Open the full advisory

RHSA-2024:2394

Vulnerability from csaf_redhat - Published: 2024-04-30 09:57 - Updated: 2026-09-11 09:26

Summary

Red Hat Security Advisory: kernel security, bug fix, and enhancement update

Severity

Important

Scope

341 vulnerabilities in this advisory, including CVE-2023-53585.

CVE-2023-53585

5.5 (Medium)


                
                  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Fixed: 279 products

https://access.redhat.com/errata/RHSA-2024:2394

Open the full advisory

SUSE-SU-2025:21040-1

Vulnerability from csaf_suse - Published: 2025-11-13 15:32 - Updated: 2025-11-13 15:32

Summary

Security update for the Linux Kernel

Severity

Important

Scope

191 vulnerabilities in this advisory, including CVE-2023-53585.

CVE-2023-53585

2.3 (Low)


                
                  CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

Recommended: 11 products

Open the full advisory

SUSE-SU-2025:21052-1

Vulnerability from csaf_suse - Published: 2025-11-25 18:51 - Updated: 2025-11-25 18:51

Summary

Security update for the Linux Kernel

Severity

Important

Scope

191 vulnerabilities in this advisory, including CVE-2023-53585.

CVE-2023-53585

2.3 (Low)


                
                  CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

Recommended: 4 products

Open the full advisory

SUSE-SU-2025:21056-1

Vulnerability from csaf_suse - Published: 2025-11-13 14:22 - Updated: 2025-11-13 14:22

Summary

Security update for the Linux Kernel

Severity

Important

Scope

191 vulnerabilities in this advisory, including CVE-2023-53585.

CVE-2023-53585

2.3 (Low)


                
                  CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

Recommended: 17 products

Open the full advisory

SUSE-SU-2025:21064-1

Vulnerability from csaf_suse - Published: 2025-11-25 16:39 - Updated: 2025-11-25 16:39

Summary

Security update for the Linux Kernel

Severity

Important

Scope

191 vulnerabilities in this advisory, including CVE-2023-53585.

CVE-2023-53585

2.3 (Low)


                
                  CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

Recommended: 7 products

Open the full advisory

SUSE-SU-2025:4057-1

Vulnerability from csaf_suse - Published: 2025-11-11 18:36 - Updated: 2025-11-11 18:36

Summary

Security update for the Linux Kernel

Severity

Important

Scope

462 vulnerabilities in this advisory, including CVE-2023-53585.

CVE-2023-53585

2.3 (Low)


                
                  CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

Recommended: 56 products

Open the full advisory

SUSE-SU-2025:4128-1

Vulnerability from csaf_suse - Published: 2025-11-18 13:51 - Updated: 2025-11-18 13:51

Summary

Security update for the Linux Kernel

Severity

Important

Scope

189 vulnerabilities in this advisory, including CVE-2023-53585.

CVE-2023-53585

2.3 (Low)


                
                  CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

Recommended: 33 products

Open the full advisory

SUSE-SU-2025:4132-1

Vulnerability from csaf_suse - Published: 2025-11-18 16:45 - Updated: 2025-11-18 16:45

Summary

Security update for the Linux Kernel

Severity

Important

Scope

462 vulnerabilities in this advisory, including CVE-2023-53585.

CVE-2023-53585

2.3 (Low)


                
                  CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

Recommended: 8 products

Open the full advisory

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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CVE-2023-53585 (GCVE-0-2023-53585)

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