What’s Vulnerable › Vulnerabilities

CVE-2018-12434

• Severity: medium (CVSS 4.7 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2018-06-15 · updated 2026-06-17
• Weakness: CWE-200

Description

LibreSSL before 2.6.5 and 2.7.x before 2.7.4 allows a memory-cache side-channel attack on DSA and ECDSA signatures, aka the Return Of the Hidden Number Problem or ROHNP. To discover a key, the attacker needs access to either the local machine or a different virtual machine on the same physical host.

Affected products

• OpenBSD Libressl: before 2.6.5; 2.7.0, 2.7.1, 2.7.2, 2.7.3 — fixed in 2.6.5

How to fix

Upgrade to a fixed version: OpenBSD Libressl 2.6.5. Check the vendor advisory for mitigations.

References

• https://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-2.6.5-relnotes.txt
• https://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-2.7.4-relnotes.txt
• https://www.nccgroup.trust/us/our-research/technical-advisory-return-of-the-hidden-number-problem/
• https://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-2.6.5-relnotes.txt
• https://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-2.7.4-relnotes.txt
• https://www.nccgroup.trust/us/our-research/technical-advisory-return-of-the-hidden-number-problem/

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