OpenSSL up to 3.4.5/3.5.6/3.6.2/4.0.0 improperly controlled sequential memory allocation

Summaryinfo

A vulnerability was found in OpenSSL up to 3.4.5/3.5.6/3.6.2/4.0.0. It has been classified as problematic. Affected is an unknown function. This manipulation causes improperly controlled sequential memory allocation. This vulnerability is tracked as CVE-2026-34183. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic was found in OpenSSL up to 3.4.5/3.5.6/3.6.2/4.0.0. Affected by this vulnerability is an unknown code block. The manipulation with an unknown input leads to a improperly controlled sequential memory allocation vulnerability. The CWE definition for the vulnerability is CWE-1325. The product manages a group of objects or resources and performs a separate memory allocation for each object, but it does not properly limit the total amount of memory that is consumed by all of the combined objects. As an impact it is known to affect availability. The summary by CVE is:

Issue summary: Remote peer may exhaust heap memory of the QUIC server or client by flooding it with packets containing PATH_CHALLENGE frames. Impact summary: A malicious remote peer can cause an unbounded memory allocation which can lead to an abnormal termination of the application acting as a QUIC client or server and a Denial of Service. A remote peer may exhaust heap memory by flooding the local QUIC stack with PATH_CHALLENGE frames. The local QUIC stack allocates a PATH_RESPONSE frame for every PATH_CHALLENGE it receives. The allocated PATH_RESPONSE frame gets freed only when the remote peer acknowledges reception of the PATH_RESPONSE frame which will not be done by a malicious peer. The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue. The QUIC stack is outside of OpenSSL FIPS module boundary.

The advisory is shared at openssl-library.org. This vulnerability is known as CVE-2026-34183 since 03/26/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 06/09/2026).

Upgrading to version 3.4.6, 3.5.7, 3.6.3 or 4.0.1 eliminates this vulnerability.

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

Productinfo

Type

• Network Encryption Software

Name

• OpenSSL

Version

• 3.4.0
• 3.4.1
• 3.4.2
• 3.4.3
• 3.4.4
• 3.4.5
• 3.5.0
• 3.5.1
• 3.5.2
• 3.5.3
• 3.5.4
• 3.5.5
• 3.5.6
• 3.6.0
• 3.6.1
• 3.6.2
• 4.0

License

• open-source

Website

• Product: https://www.openssl.org/

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

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