boazsegev facil.io up to 0.7.6 Multipart MIME Body Parser http_mime_parser.h integer underflow

Summaryinfo

A vulnerability marked as critical has been reported in boazsegev facil.io up to 0.7.6. This impacts an unknown function of the file http_mime_parser.h of the component Multipart MIME Body Parser. The manipulation leads to integer underflow. This vulnerability is listed as CVE-2026-66729. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in boazsegev facil.io up to 0.7.6 and classified as critical. This issue affects an unknown code of the file http_mime_parser.h of the component Multipart MIME Body Parser. The manipulation with an unknown input leads to a integer underflow vulnerability. Using CWE to declare the problem leads to CWE-191. The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

facil.io 0.6.0 through 0.7.6 contains an integer underflow vulnerability in the multipart MIME body parser that allows unauthenticated remote attackers to crash the server process by sending a crafted Content-Disposition header with an empty field name. Attackers can trigger a uint32_t wraparound in http_mime_parser.h causing an out-of-bounds memory read past the name pointer, resulting in a bus fault that crashes the handling worker with a single POST request.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-66729 since 07/27/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/27/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• boazsegev

Name

• facil.io

Version

• 0.7.0
• 0.7.1
• 0.7.2
• 0.7.3
• 0.7.4
• 0.7.5
• 0.7.6

CPE 2.3info

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• 🔒
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CPE 2.2info

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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