CVE-2026-7531
Undergoing Analysis Undergoing Analysis - In Progress
Use-after-free in wolfSSL PQC Hybrid KeyShare Handling

Publication date: 2026-06-25

Last updated on: 2026-06-25

Assigner: wolfSSL Inc.

Description
Use-after-free in PQC hybrid key-share handling. This is an incomplete-fix follow-up to CVE-2026-5460 (released in 5.9.1): a malicious TLS 1.3 server sending a truncated PQC hybrid KeyShare can still trigger the error cleanup path to operate on freed memory.
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Meta Information
Published
2026-06-25
Last Modified
2026-06-25
Generated
2026-06-26
AI Q&A
2026-06-25
EPSS Evaluated
N/A
NVD
CVE-2026-7531
EUVD
EUVD-2026-39554
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
wolfssl wolfssl From 5.9.1 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-416 The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
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Impact Analysis

The vulnerability can lead to memory corruption due to use-after-free, which may be exploited by an attacker to cause a denial of service or potentially execute arbitrary code. However, the CVSS base score is low (2.3), indicating that the impact is limited and requires a high attack complexity with user interaction.

Executive Summary

This vulnerability is a use-after-free issue in the handling of PQC (Post-Quantum Cryptography) hybrid key-share during TLS 1.3 connections. It is a follow-up to a previous vulnerability (CVE-2026-5460) and occurs when a malicious TLS 1.3 server sends a truncated PQC hybrid KeyShare. This can cause the error cleanup process to operate on memory that has already been freed, potentially leading to undefined behavior.

Compliance Impact

The provided information does not specify any direct impact of CVE-2026-7531 on compliance with common standards and regulations such as GDPR or HIPAA.

Detection Guidance

Detection of this vulnerability involves identifying malformed TLS 1.3 PQC hybrid KeyShare messages, specifically those with malformed ECDH portions that could trigger use-after-free conditions.

A regression test named `test_tls13_pqc_hybrid_malformed_ecdh` was created to simulate such malformed key shares and verify the fix.

While no specific network commands are provided, monitoring TLS 1.3 handshake messages for truncated or malformed PQC hybrid KeyShare extensions could help detect attempts to exploit this vulnerability.

Mitigation Strategies

The immediate mitigation is to update the wolfSSL library to a version that includes the hardening fix for this vulnerability.

The fix involves clearing the key pointer after non-async/non-pending hybrid ECDH processing to prevent double-free or use-after-free conditions.

Applying this patch will prevent the cleanup code from operating on already-freed memory, thus mitigating the vulnerability.

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