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CVE-2023-3724

TLS 1.3 client issue handling malicious server when not including a KSE and PSK extension

9.1 CriticalFix available

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
High
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.65%Up 0.6 points since Jul 18, 2023
90%50%10%1%

What each source reports

CVE List Score used 9.1

TLS 1.3 client issue handling malicious server when not including a KSE and PSK extension

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used. 

Record
CVE-2023-3724
CVSS 3.1
9.1 CriticalCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-20
Updated
2026-11-02
EUVDEUVD-2023-44359 9.1

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used. 

Record
EUVD-2023-44359
CVSS 3.1
9.1 CriticalCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-03
GitHub AdvisoriesGHSA-h4rv-393v-2f5h 9.1

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension)...

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used. 

Record
GHSA-h4rv-393v-2f5h
CVSS 3.1
9.1 CriticalCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-20, CWE-295
Updated
2026-11-02
NVD 9.1

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used. 

Record
CVE-2023-3724
CVSS 3.1
9.1 CriticalCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-20, CWE-295
Updated
2026-11-02
OSVALPINE-CVE-2023-3724 8.8

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used. 

Record
ALPINE-CVE-2023-3724
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-03
OSVAZL-27649 8.8

CVE-2023-3724 affecting package mariadb for versions less than 10.6.9-3.cm2

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used. 

Record
AZL-27649
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
Show 5 moreShow less
OSVBELL-CVE-2023-3724 8.8

CVE-2023-3724 does not affect BellSoft software

Record
BELL-CVE-2023-3724
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSV 9.1

TLS 1.3 client issue handling malicious server when not including a KSE and PSK extension

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used. 

Record
CVE-2023-3724
CVSS 3.1
9.1 CriticalCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-20
Updated
2026-11-02
OSVDEBIAN-CVE-2023-3724 8.8

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used.

Record
DEBIAN-CVE-2023-3724
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVJLSEC-2026-676 8.8

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension)...

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used.

Record
JLSEC-2026-676
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2023-3724 9.1

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used.

Record
UBUNTU-CVE-2023-3724
CVSS 3.1
9.1 CriticalCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
wolfssl
Alpine:v3.18
before 5.6.2-r0
5.6.2-r0
wolfssl
Alpine:v3.19
before 5.6.2-r0
5.6.2-r0
wolfssl
Alpine:v3.20
before 5.6.2-r0
5.6.2-r0
wolfssl
Alpine:v3.21
before 5.6.2-r0
5.6.2-r0
wolfssl
Alpine:v3.22
before 5.6.2-r0
5.6.2-r0
wolfssl
Alpine:v3.23
before 5.6.2-r0
5.6.2-r0
wolfssl
Alpine:v3.24
before 5.6.2-r0
5.6.2-r0
mariadb
Azure Linux:2
before 10.6.9-3.cm2
10.6.9-3.cm2
wolfssl
Debian:12
before 5.5.4-2+deb12u1, plus listed versions
5.5.4-2
5.5.4-2+deb12u1
wolfssl
Debian:13
before 5.5.4-2.1
5.5.4-2.1
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Affected packages
PackageAffectedFixed
wolfSSL_jll
Julia
before 5.7.2+0
5.7.2+0
wolfssl
Ubuntu:16.04:LTS
All versions, plus listed versions
3.4.8+dfsg-1
None known
wolfssl
Ubuntu:18.04:LTS
All versions, plus listed versions
3.10.2+dfsg-23.12.0+dfsg-13.12.2+dfsg-13.13.0+dfsg-1
None known
wolfssl
Ubuntu:20.04:LTS
All versions, plus listed versions
4.1.0+dfsg-24.2.0+dfsg-14.2.0+dfsg-24.2.0+dfsg-34.3.0+dfsg-2
None known
wolfssl
Ubuntu:22.04:LTS
All versions, plus listed versions
4.6.0-35.0.0-15.1.1-15.2.0-15.2.0-2
None known
wolfssl
Ubuntu:24.04:LTS
All versions, plus listed versions
5.5.4-25.5.4-2.15.6.4-25.6.6-1.25.6.6-1.35.6.6-1.3build1
None known
wolfssl
Ubuntu:25.10
All versions, plus listed versions
5.7.2-0.1
None known
wolfssl
Ubuntu:26.10
All versions, plus listed versions
5.9.1-0.15.9.2-1
None known
wolfssl
Ubuntu:26.04:LTS
All versions, plus listed versions
5.7.2-0.15.8.2-1.25.8.4-15.9.1-0.1
None known

History

History
RecordedChangedSources
affected, aliases, referencesOSV
publishedEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2023-3724 is a critical vulnerability (CVSS 9.1) in Wolfssl, published July 17, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.65%, the 51st percentile. Fixed in wolfssl 5.6.2-r0.

References

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