Datadog Security Labs
OpenSSL January 2026 Security Update: CMS and PKCS#12 Buffer Overflows
ATT&CK techniques detected
T1573.002Asymmetric Cryptography
63%
“##mp $ openssl version openssl 3. 0. 2 15 mar 2022 ( library : openssl 3. 0. 2 15 mar 2022 ) nick @ test - cattle : / tmp $ openssl cms - decrypt \ - in temp / encdatawithtoolongiv. pem \ - inform pem \ - recip temp / servercert. pem \ - inkey temp / serverkey. pem - noout * * * …”
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T1505.003Web Shell
37%
“unfamiliar process created by web application - shell process created by java application - interactive shell spawned in container detect with service checks ( dos scenario ) for denial - of - service scenarios, repeated crashes or restarts of services processing cms or pkcs # 12…”
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Summary
A deep dive into OpenSSL’s January 2026 CMS and PKCS#12 vulnerabilities, including a pre-auth stack overflow and a PKCS#12 parsing bug.