Stack Overflow in libcurl via Deeply Nested MIME Structure
CVE-2026-92391 Published on October 20, 2026

curl_mime_free stack overflow by recursion
A deeply nested multipart MIME structure constructed via the public API causes a stack overflow in libcurl during normal cleanup operations. An excessive recursion depth within `curl_mime_free` leads to unbounded stack frame allocation during structure traversal, ultimately crashing the host process.

NVD

A proof of concept, or POC exists for this vulnerability which can be automated.

Vulnerability Analysis

CVE-2026-92391 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. An automatable proof of concept (POC) exploit exists. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.

Exploitation:
POC
Automatable:
YES
Technical Impact:
PARTIAL
Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
HIGH

Weakness Type

What is a Stack Exhaustion Vulnerability?

The product does not properly control the amount of recursion which takes place, consuming excessive resources, such as allocated memory or the program stack.

CVE-2026-92391 has been classified to as a Stack Exhaustion vulnerability or weakness.


Products Associated with CVE-2026-92391

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Canonical Ubuntu Linux
Haxx Curl

Affected Versions

curl: