CVE-2026-92391: curl_mime_free stack overflow by recursion

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-20 · updated 2026-10-30
Weakness: CWE-674

Description

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.

Affected products

curl: from 8.22.0 through 8.22.0; from 8.21.0 through 8.21.0; from 8.20.0 through 8.20.0; from 8.19.0 through 8.19.0; from 8.18.0 through 8.18.0; from 8.17.0 through 8.17.0

References

https://curl.se/docs/CVE-2026-92391.html
https://curl.se/docs/CVE-2026-92391.json
https://hackerone.com/reports/4024222
https://hackerone.com/reports/4024222

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