CVE-2026-45541Network attack vector

Unauthenticated device crash via null token dereference

Published Jun 10, 2026 · Updated Jun 10, 2026

NULL-pointer dereference in ESP-IDF 5.2.6, 5.3.5, 5.4.4, 5.5.4, and 6.0 allows remote attackers to crash WebSocket servers. The httpd_ws_get_response_subprotocol() parsing loop dereferences a null strtok_r result while processing a malformed Sec-WebSocket-Protocol header. Reachability requires WebSocket support and a registered URI handler with subprotocol negotiation; the device faults before application authentication, without disclosure or writes.

CVSS severity7.5
High
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL-pointer dereference in ESP-IDF 5.2.6, 5.3.5, 5.4.4, 5.5.4, and 6.0 allows remote attackers to crash WebSocket servers. The httpd_ws_get_response_subprotocol() parsing loop dereferences a null strtok_r result while processing a malformed Sec-WebSocket-Protocol header. Reachability requires WebSocket support and a registered URI handler with subprotocol negotiation; the device faults before application authentication, without disclosure or writes.

The record

CVE
CVE-2026-45541
Published
Jun 10, 2026
Updated
Jun 10, 2026
Vendor
Espressif Systems
Product
ESP-IDF
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 10, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion== 5.2.6
  2. Affected versionversion== 5.3.5
  3. Affected versionversion== 5.4.4
  4. Affected versionversion== 5.5.4
  5. Affected versionversion== 6.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Espressif Systems · ESP-IDFversion== 5.2.6; version== 5.3.5; version== 5.4.4; version== 5.5.4; version== 6.0

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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