CVE-2026-45541

CVE-2026-45541 is a high-severity vulnerability in Espressif Esp-idf with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-476.

Key facts

• Severity: High (CVSS 3.x base score 7.5)
• EPSS exploit prediction: 0% (35th percentile)
• Actively exploited: Not listed in CISA KEV
• EU (EUVD) id: EUVD-2026-35914
• Weakness: CWE-476
• Affected product: Espressif Esp-idf
• Published: 2026-06-10
• Last modified: 2026-06-17

Description

ESF-IDF is the Espressif Internet of Things (IOT) Development Framework. In versions 5.2.6, 5.3.5, 5.4.4, 5.5.4, and 6.0, a NULL-pointer dereference exists in the WebSocket subprotocol-negotiation path of the esp_http_server component. While parsing the client-supplied Sec-WebSocket-Protocol request header during the WebSocket handshake, the tokenisation result is dereferenced without a NULL check, so a malformed header value can crash the server before any application-level authentication runs. This issue has been patched in versions 5.2.7, 5.3.6, 5.4.5, 5.5.5, and 6.0.1.

Frequently asked questions

What is CVE-2026-45541?

ESF-IDF is the Espressif Internet of Things (IOT) Development Framework. In versions 5.2.6, 5.3.5, 5.4.4, 5.5.4, and 6.0, a NULL-pointer dereference exists in the WebSocket subprotocol-negotiation path of the esp_http_server component. While parsing the client-supplied Sec-WebSocket-Protocol request header during the WebSocket handshake, the tokenisation result is dereferenced without a NULL check, so a malformed header value can crash the server before any application-level authentication runs. This issue has been patched in versions 5.2.7, 5.3.6, 5.4.5, 5.5.5, and 6.0.1.

How severe is CVE-2026-45541?

CVE-2026-45541 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-45541 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-45541?

CVE-2026-45541 primarily affects Espressif Esp-idf. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-45541?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-45541 have an EU (EUVD) identifier?

Yes. CVE-2026-45541 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-35914.

When was CVE-2026-45541 published?

CVE-2026-45541 was published on 2026-06-10 and last updated on 2026-06-17.

References

• https://github.com/espressif/esp-idf/commit/00a2f7fbbbd8fe6d04729022e1d5c9a49435bfe8
• https://github.com/espressif/esp-idf/commit/0dc4ee7537f3b12350f5966cecacd59bba840ec6
• https://github.com/espressif/esp-idf/commit/37508ab91124ef426a7396d30f79eba1162700c7
• https://github.com/espressif/esp-idf/commit/9fc0ca13b3b85b98d32b98cd9dc8ff9d82642b7b
• https://github.com/espressif/esp-idf/commit/dc46dc51359749e50617eb70d6f9ae298adc4fff
• https://github.com/espressif/esp-idf/commit/f88a47e4f37fb11ae4b0908cd5c80059d83198c6
• https://github.com/espressif/esp-idf/security/advisories/GHSA-3j8v-xgrq-5vg8

Affected products (5)

• cpe:2.3:a:espressif:esp-idf:5.2.6:*:*:*:*:*:*:*
• cpe:2.3:a:espressif:esp-idf:5.3.5:*:*:*:*:*:*:*
• cpe:2.3:a:espressif:esp-idf:5.4.4:*:*:*:*:*:*:*
• cpe:2.3:a:espressif:esp-idf:5.5.4:*:*:*:*:*:*:*
• cpe:2.3:a:espressif:esp-idf:6.0:*:*:*:*:*:*:*

More vulnerabilities in Espressif Esp-idf

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• CVE-2010-2495 — Critical (CVSS 10.0): The pppol2tp_xmit function in drivers/net/pppol2tp.c in the L2TP implementation in the Linux kernel before 2.6.34 does…
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