ESF-IDF: Remote Null Pointer Dereference in WebSocket Server

published 2026-06-10 5 mo ago modified 2026-07-23 3 mo ago also EUVD-2026-35914

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits: 0; none known

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.

Patch / fix

links 7

github.com/espressif/esp-idf@00a2f7f commit
github.com/espressif/esp-idf@0dc4ee7 commit
github.com/espressif/esp-idf@37508ab commit
github.com/espressif/esp-idf@9fc0ca1 commit
github.com/espressif/esp-idf@dc46dc5 commit
github.com/espressif/esp-idf@f88a47e commit
github.com/espressif/esp-idf/security/advisories/GHSA-3j8v-xgrq-5vg8 advisory

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 4 mo ago (2026-06-10)

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

espressif esp-idf

Classification

Weakness

CWE-476 NULL Pointer Dereference

References

Sources

CVE List CVE-2026-45541
NVD CVE-2026-45541

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary