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Fencer Vulns
critical 9.1

CVE-2023-3724 json

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

published 2023-07-17 3 y ago modified 2026-07-18 3 mo ago also EUVD-2023-44359 , GHSA-h4rv-393v-2f5h , JLSEC-2026-676

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 51%
public exploits
0
none known

Summary

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.

Patch / fix

  • julia wolfSSL_jll 5.7.2+0
  • wolfssl wolfssl 5.6.2
  • wolfssl Debian 12 5.5.4-2+deb12u1
  • wolfssl Debian 13 5.5.4-2.1

debian advisories DEBIAN-CVE-2023-3724

  • wolfssl Alpine 3.24, Alpine 3.23, Alpine 3.22 +4 more 5.6.2-r0

alpine advisories ALPINE-CVE-2023-3724

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • mariadb CBL-Mariner 2.0 10.6.9-3.cm2

azure linux advisories AZL-27649

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
2 y ago

Exploit prediction

0.65% chance of exploitation in the next 30 days, higher than 51% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
OSV 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
julia wolfSSL_jll
<5.7.2+0
5.7.2+0

Affected products

  • wolfSSL wolfSSL

Classification

Weakness
  • CWE-20 Improper Input Validation
  • CWE-295 Improper Certificate Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.