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GHSA-C96V-VVF3-2P7R

Vulnerability from github – Published: 2026-03-10 18:31 – Updated: 2026-04-02 15:31

Details

In the Linux kernel, the following vulnerability has been resolved:

tls: Fix race condition in tls_sw_cancel_work_tx()

This issue was discovered during a code audit.

After cancel_delayed_work_sync() is called from tls_sk_proto_close(), tx_work_handler() can still be scheduled from paths such as the Delayed ACK handler or ksoftirqd. As a result, the tx_work_handler() worker may dereference a freed TLS object.

The following is a simple race scenario:

      cpu0                         cpu1

tls_sk_proto_close() tls_sw_cancel_work_tx() tls_write_space() tls_sw_write_space() if (!test_and_set_bit(BIT_TX_SCHEDULED, &tx_ctx->tx_bitmask)) set_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask); cancel_delayed_work_sync(&ctx->tx_work.work); schedule_delayed_work(&tx_ctx->tx_work.work, 0);

To prevent this race condition, cancel_delayed_work_sync() is replaced with disable_delayed_work_sync().

Severity

9.8 (Critical)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-23240"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-362"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-03-10T18:18:13Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntls: Fix race condition in tls_sw_cancel_work_tx()\n\nThis issue was discovered during a code audit.\n\nAfter cancel_delayed_work_sync() is called from tls_sk_proto_close(),\ntx_work_handler() can still be scheduled from paths such as the\nDelayed ACK handler or ksoftirqd.\nAs a result, the tx_work_handler() worker may dereference a freed\nTLS object.\n\nThe following is a simple race scenario:\n\n          cpu0                         cpu1\n\ntls_sk_proto_close()\n  tls_sw_cancel_work_tx()\n                                 tls_write_space()\n                                   tls_sw_write_space()\n                                     if (!test_and_set_bit(BIT_TX_SCHEDULED, \u0026tx_ctx-\u003etx_bitmask))\n    set_bit(BIT_TX_SCHEDULED, \u0026ctx-\u003etx_bitmask);\n    cancel_delayed_work_sync(\u0026ctx-\u003etx_work.work);\n                                     schedule_delayed_work(\u0026tx_ctx-\u003etx_work.work, 0);\n\nTo prevent this race condition, cancel_delayed_work_sync() is\nreplaced with disable_delayed_work_sync().",
  "id": "GHSA-c96v-vvf3-2p7r",
  "modified": "2026-04-02T15:31:35Z",
  "published": "2026-03-10T18:31:19Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23240"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/17153f154f80be2b47ebf52840f2d8f724eb2f3b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7bb09315f93dce6acc54bf59e5a95ba7365c2be4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/854cd32bc74fe573353095e90958490e4e4d641b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a5de36d6cee74a92c1a21b260bc507e64bc451de"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-23240 (GCVE-0-2026-23240)

Vulnerability from cvelistv5 – Published: 2026-03-10 17:28 – Updated: 2026-10-19 18:35

Title

tls: Fix race condition in tls_sw_cancel_work_tx()

Summary

In the Linux kernel, the following vulnerability has been resolved: tls: Fix race condition in tls_sw_cancel_work_tx() This issue was discovered during a code audit. After cancel_delayed_work_sync() is called from tls_sk_proto_close(), tx_work_handler() can still be scheduled from paths such as the Delayed ACK handler or ksoftirqd. As a result, the tx_work_handler() worker may dereference a freed TLS object. The following is a simple race scenario: cpu0 cpu1 tls_sk_proto_close() tls_sw_cancel_work_tx() tls_write_space() tls_sw_write_space() if (!test_and_set_bit(BIT_TX_SCHEDULED, &tx_ctx->tx_bitmask)) set_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask); cancel_delayed_work_sync(&ctx->tx_work.work); schedule_delayed_work(&tx_ctx->tx_work.work, 0); To prevent this race condition, cancel_delayed_work_sync() is replaced with disable_delayed_work_sync().

Severity

9.8 (Critical)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-16 15:06 UTC

CWE

CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6637 records in the last 180 days details

References

4 references

URL	Tags
https://git.kernel.org/stable/c/a5de36d6cee74a92c…
https://git.kernel.org/stable/c/854cd32bc74fe5733…
https://git.kernel.org/stable/c/17153f154f80be2b4…
https://git.kernel.org/stable/c/7bb09315f93dce6ac…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: f87e62d45e51b12d48d2cb46b5cde8f83b866bc4 , < a5de36d6cee74a92c1a21b260bc507e64bc451de (git) Affected: f87e62d45e51b12d48d2cb46b5cde8f83b866bc4 , < 854cd32bc74fe573353095e90958490e4e4d641b (git) Affected: f87e62d45e51b12d48d2cb46b5cde8f83b866bc4 , < 17153f154f80be2b47ebf52840f2d8f724eb2f3b (git) Affected: f87e62d45e51b12d48d2cb46b5cde8f83b866bc4 , < 7bb09315f93dce6acc54bf59e5a95ba7365c2be4 (git)
Linux	Linux	Affected: 5.3 Unaffected: 0 , < 5.3 (semver) Unaffected: 6.12.75 , ≤ 6.12.* (semver) Unaffected: 6.18.16 , ≤ 6.18.* (semver) Unaffected: 6.19.6 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix)

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JSON

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                "id": "CVE-2026-23240",
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                "timestamp": "2026-10-16T15:06:53.340021Z",
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntls: Fix race condition in tls_sw_cancel_work_tx()\n\nThis issue was discovered during a code audit.\n\nAfter cancel_delayed_work_sync() is called from tls_sk_proto_close(),\ntx_work_handler() can still be scheduled from paths such as the\nDelayed ACK handler or ksoftirqd.\nAs a result, the tx_work_handler() worker may dereference a freed\nTLS object.\n\nThe following is a simple race scenario:\n\n          cpu0                         cpu1\n\ntls_sk_proto_close()\n  tls_sw_cancel_work_tx()\n                                 tls_write_space()\n                                   tls_sw_write_space()\n                                     if (!test_and_set_bit(BIT_TX_SCHEDULED, \u0026tx_ctx-\u003etx_bitmask))\n    set_bit(BIT_TX_SCHEDULED, \u0026ctx-\u003etx_bitmask);\n    cancel_delayed_work_sync(\u0026ctx-\u003etx_work.work);\n                                     schedule_delayed_work(\u0026tx_ctx-\u003etx_work.work, 0);\n\nTo prevent this race condition, cancel_delayed_work_sync() is\nreplaced with disable_delayed_work_sync()."
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              "value": "AV:N - The tls_write_space callback is triggered by a remote TCP peer sending ACKs, which causes tcp_data_snd_check \u2192 tcp_check_space \u2192 tcp_new_space \u2192 sk-\u003esk_write_space (tls_write_space). Any server using kTLS (nginx, HAProxy, NFS with TLS) is reachable over the network.\nAC:L - The attacker controls both sides of the race: they send TCP ACKs to trigger tls_write_space and initiate disconnect to trigger the close path. With repeated connection attempts and ACK flooding, the race window is reliably winnable.\nPR:N - No authentication or privileges are needed to establish a TCP connection and send ACKs to a kTLS-enabled server. The race is triggered during normal TCP processing before any application-level authentication occurs.\nUI:N - No user interaction is needed. The attacker connects to the server, sends ACKs, and disconnects to trigger the race. The server processes this automatically.\nS:U - The vulnerability results in kernel-level use-after-free within the same security authority (kernel space). There is no crossing of a virtualization or sandbox boundary.\nC:H - This is a use-after-free where the freed tls_sw_context_tx (freed via immediate kfree, not kfree_rcu) can be reallocated with attacker-influenced data. The UAF gives read access to reallocated memory contents, enabling arbitrary kernel memory disclosure.\nI:H - The UAF on the tls_sw_context_tx structure enables heap spraying to control the freed object\u0027s contents. The tx_work_handler then calls tls_tx_records through corrupted context pointers, enabling control flow hijacking and arbitrary code execution.\nA:H - The use-after-free on the embedded delayed_work struct causes kernel crashes when the workqueue attempts to execute the freed work item, resulting in kernel panic or oops."
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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.

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