Is CVE-2026-82391 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-82391 being exploited in the wild.

How severe is CVE-2026-82391?

Critical severity, with a CVSS score of 9.1, published 10 November 2026.

Which products and versions are affected?

Zephyr Project Zephyr versions with CONFIG_HTTP_SERVER_VERSION_2 enabled (default) and CONFIG_FILE_SYSTEM=y and HTTP_RESOURCE_TYPE_STATIC_FS registered.

Is there a fix for CVE-2026-82391?

Yes: fixed in Fixed in subsys/net/lib/http/http_server_http2.c by using a local size_t variable for file_size instead of aliasing client->data_len. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-82391 attacked?

It is attacked over the network, in an operating system.

Am I affected by CVE-2026-82391?

Check whether you run Zephyr Project Zephyr at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-82391: Zephyr HTTP server HTTP/2 buffer overflow via static file serving

CVE-2026-82391 · Severity: critical · CVSS 9.1 · Published 2026-11-10

Zephyr is an open-source real-time operating system used in embedded devices and IoT applications. An unauthenticated attacker can trigger a memory corruption vulnerability in the HTTP/2 server by requesting a static file, allowing them to crash the device or potentially execute arbitrary code on the system.

Technologies: Zephyr Project Zephyr. Vendors: Zephyr Project.

Quick answers

Is CVE-2026-82391 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-82391 being exploited in the wild.
How severe is CVE-2026-82391?: Critical severity, with a CVSS score of 9.1, published 10 November 2026.
Which products and versions are affected?: Zephyr Project Zephyr versions with CONFIG_HTTP_SERVER_VERSION_2 enabled (default) and CONFIG_FILE_SYSTEM=y and HTTP_RESOURCE_TYPE_STATIC_FS registered.
Is there a fix for CVE-2026-82391?: Yes: fixed in Fixed in subsys/net/lib/http/http_server_http2.c by using a local size_t variable for file_size instead of aliasing client->data_len. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-82391 attacked?: It is attacked over the network, in an operating system.
Am I affected by CVE-2026-82391?: Check whether you run Zephyr Project Zephyr at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: Fixed in subsys/net/lib/http/http_server_http2.c by using a local size_t variable for file_size instead of aliasing client->data_len

Technical details

The HTTP/2 handler in Zephyr's HTTP server passes a connection's receive buffer length variable to be overwritten with the requested file's on-disk size. Once this variable exceeds the 256-byte buffer, subsequent frame parsing reads past the buffer boundary and a memmove operation during request handling overflows the buffer, corrupting adjacent control structures and other client contexts in static memory. An unauthenticated network attacker can trigger this by sending an HTTP/2 GET request for any file in the configured web root when static filesystem resources are enabled.

Affected products

Zephyr Project Zephyr versions with CONFIG_HTTP_SERVER_VERSION_2 enabled (default) and CONFIG_FILE_SYSTEM=y and HTTP_RESOURCE_TYPE_STATIC_FS registered

Timeline

2026-11-10: disclosed

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