CVE-2026-7531Network attack vector

Client crash via malformed PQC hybrid KeyShare

Published Jun 25, 2026 · Updated Jun 25, 2026

Use-after-free in wolfSSL 5.8.0 through 5.9.1 allows remote attackers to crash clients via a malformed TLS 1.3 hybrid KeyShare. TLSX_KeyShare_ProcessPqcHybridClient leaves keyShareEntry->key pointing to a freed malformed ECDH key, so later error cleanup frees it again. Exploitation requires a wolfSSL client with PQC hybrid key exchange enabled to connect to an attacker-controlled TLS 1.3 server; the bounded result is a client process crash.

CVSS severity2.3
Low
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in wolfSSL 5.8.0 through 5.9.1 allows remote attackers to crash clients via a malformed TLS 1.3 hybrid KeyShare. TLSX_KeyShare_ProcessPqcHybridClient leaves keyShareEntry->key pointing to a freed malformed ECDH key, so later error cleanup frees it again. Exploitation requires a wolfSSL client with PQC hybrid key exchange enabled to connect to an attacker-controlled TLS 1.3 server; the bounded result is a client process crash.

The record

CVE
CVE-2026-7531
Published
Jun 25, 2026
Updated
Jun 25, 2026
Vendor
wolfSSL
Product
wolfSSL
Classifications
CWE-416, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=5.8.0 <=5.9.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

wolfSSL · wolfSSLversion=5.8.0 <=5.9.1

Published CVSS scores

2.3wolfSSL Inc.CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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