CVE-2026-45541: ESF-IDF is the Espressif Internet of Things (IOT) Development Framework

This month

HIGH 7.5REMOTEDOWNGRADE

CVE-2026-45541 is a high-severity flaw (CVSS 7.5) affecting esp-idf. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 62%)
CISA exploited list	No
Weakness	CWE-476
Published	2026-06-10
Last modified	2026-07-23

Publisher (CNA): GitHub, Inc. · Vendor: espressif

Last updated 2026-07-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-10 02:16 UTCPublished CVE record published
2026-07-23 09:10 UTCUpdated Record last modified

espressif esp-idf DOWNGRADE

Affected: 5.2.6 · 5.3.5 · 5.4.4 · 5.5.4 · 6.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.2.6

1. Check installed version

apt-cache policy esp-idf || rpm -q esp-idf || esp-idf --version

2. No fixed release: DOWNGRADE to a release before 5.2.6 (Debian / Ubuntu)

apt-cache madison esp-idf sudo apt install esp-idf=<VERSION_BEFORE_5.2.6> sudo apt-mark hold esp-idf

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list esp-idf sudo dnf downgrade esp-idf-<VERSION_BEFORE_5.2.6> sudo dnf versionlock add esp-idf

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-45541?

esp-idf: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-45541 being exploited?

CVE-2026-45541 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-45541 affect?

CVE-2026-45541 affects esp-idf. Severity is high (CVSS 7.5). 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. Whil

How urgent is CVE-2026-45541?

Priority 41/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-45328 CRITICAL 9.3 DOWNGRADE ESF-IDF is the Espressif Internet of Things (IOT) Development Framework
CVE-2026-45542 HIGH 7.1 DOWNGRADE ESF-IDF is the Espressif Internet of Things (IOT) Development Framework
CVE-2026-45160 MEDIUM 6.5 DOWNGRADE ESF-IDF is the Espressif Internet of Things (IOT) Development Framework
CVE-2026-45329 HIGH 7.1 DOWNGRADE ESF-IDF is the Espressif Internet of Things (IOT) Development Framework
CVE-2026-46532 MEDIUM 4.6 DOWNGRADE ESF-IDF is the Espressif Internet of Things (IOT) Development Framework

References

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