CVE Intelligence
Analysis AI-assisted

CVE-2026-7531: wolfSSL: use-after-free in PQC hybrid key share handling during TLS 1.3

CVE-2026-7531 is a use-after-free (CWE-416) in wolfSSL's handling of post-quantum hybrid key shares in TLS 1.3. The record describes it as an incomplete-fix follow-up to CVE-2026-5460, and NVD scores it 9.8 (critical) under CVSS 3.1. A patch is referenced in the wolfSSL pull request, and the record shows no confirmed exploitation.

Published Oct 13, 2026 · Updated Oct 13, 2026 · Ler em português

Overview

CVE-2026-7531 is a use-after-free weakness (CWE-416) in how wolfSSL handles post-quantum cryptography (PQC) hybrid key shares during TLS 1.3 negotiation. According to the record, it is an incomplete-fix follow-up to CVE-2026-5460, which was released in wolfSSL 5.9.1. The record attributes the report to the CNA facts@wolfssl.com.

Impact

  • The record states that a malicious TLS 1.3 server sending a truncated PQC hybrid KeyShare can still cause the error cleanup path to operate on freed memory.
  • NVD lists a CVSS 3.1 base score of 9.8 (critical) with vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
  • The CNA provided a separate CVSS 4.0 score of 2.3. The record does not explain the difference between the two scores.
  • The consequences beyond the memory-safety condition described in the record are not detailed in the sources consulted.

Affected products and versions

  • Product listed as Wolfssl Wolfssl.
  • Range listed as 5.8.0 or later and before 5.9.2.
  • Versions outside this range are not listed as affected in the record. The record does not list specific fixed version numbers beyond this range boundary.

Exploitation status

  • The CISA KEV catalog entry is marked as not listed, so this record does not confirm active exploitation.
  • No EPSS score or SSVC decision is present in the record.
  • No confirmed exploitation appears in the sources consulted for this analysis.

Remediation and mitigation

  • Review the wolfSSL security vulnerabilities page and the referenced pull request for the fix and the version that contains it.
  • Plan upgrades of wolfSSL builds in the listed range, prioritizing systems where TLS 1.3 with PQC hybrid key exchange is enabled and where clients connect to untrusted servers.
  • Because the record describes a follow-up to a previous fix, verify that the installed version includes both the CVE-2026-5460 and CVE-2026-7531 corrections rather than relying on the earlier release alone.
  • Rebuild and redeploy applications that statically link wolfSSL after updating.

Detection guidance

  • Inventory systems and embedded or appliance products that bundle wolfSSL and record their exact versions.
  • Monitor TLS client processes for unexpected crashes or memory-safety faults during handshakes with external servers, and review logs around those events.
  • Restrict outbound TLS connections from sensitive services to known endpoints where practical, reducing exposure to untrusted servers.

Limitations of the available information

  • The record does not describe the exact conditions required to reach the vulnerable path, such as which build options or configurations enable PQC hybrid key shares.
  • The record does not provide the exact fixed version number, only the upper boundary of the affected range and a patch reference.
  • The reason for the CVSS 4.0 score of 2.3 is not given.
  • The full text of the vendor advisory was not included in the record, so details beyond the summary are unknown.

Frequently asked questions

What kind of vulnerability is CVE-2026-7531?

It is a use-after-free (CWE-416) in wolfSSL's handling of PQC hybrid key shares during TLS 1.3. The record says the error cleanup path can operate on freed memory.

Which wolfSSL versions are listed as affected?

The record lists versions 5.8.0 or later and before 5.9.2. It also says CVE-2026-5460 was released in 5.9.1 and that CVE-2026-7531 is an incomplete-fix follow-up.

Is this vulnerability known to be exploited?

The CISA KEV entry is marked as not listed, and no confirmed exploitation appears in the sources consulted for this analysis.

This analysis was drafted with AI assistance from verified source data and automatically checked against it.