CVE-2026-5460Network attack vector

Client heap corruption via double-free cleanup

Published Apr 9, 2026 · Updated Apr 9, 2026

Use-after-free in wolfSSL before 5.9.1 allows remote attackers controlling a TLS 1.3 server to corrupt client heap memory. In TLSX_KeyShare_ProcessPqcHybridClient() in src/tls.c, an inner error path frees a KyberKey before TLSX_KeyShare_FreeAll() zeros and frees the same object again. Exploitation requires a wolfSSL TLS 1.3 client with PQC hybrid KeyShare support to process a truncated ServerHello; published impact is limited heap modification and service interruption.

CVSS severity6.3
Medium
EPSS probability0.21%
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 before 5.9.1 allows remote attackers controlling a TLS 1.3 server to corrupt client heap memory. In TLSX_KeyShare_ProcessPqcHybridClient() in src/tls.c, an inner error path frees a KyberKey before TLSX_KeyShare_FreeAll() zeros and frees the same object again. Exploitation requires a wolfSSL TLS 1.3 client with PQC hybrid KeyShare support to process a truncated ServerHello; published impact is limited heap modification and service interruption.

The record

CVE
CVE-2026-5460
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
wolfSSL
Product
wolfSSL
Classifications
CWE-416, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <5.9.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

wolfSSL · wolfSSLversion=0 <5.9.1

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
6.3wolfSSL Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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