What’s Vulnerable › Vulnerabilities

CVE-2018-20187

• Severity: medium (CVSS 5.9 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-03-08 · updated 2026-06-17
• Weakness: CWE-320

Description

A side-channel issue was discovered in Botan before 2.9.0. An attacker capable of precisely measuring the time taken for ECC key generation may be able to derive information about the high bits of the secret key, as the function to derive the public point from the secret scalar uses an unblinded Montgomery ladder whose loop iteration count depends on the bitlength of the secret. This issue affects only key generation, not ECDSA signatures or ECDH key agreement.

Affected products

• randombit botan: before 2.9.0 — fixed in 2.9.0

How to fix

Upgrade to a fixed version: randombit botan 2.9.0. Check the vendor advisory for mitigations.

References

• https://botan.randombit.net/news.html
• https://botan.randombit.net/security.html
• https://github.com/crocs-muni/ECTester
• https://botan.randombit.net/news.html
• https://botan.randombit.net/security.html
• https://github.com/crocs-muni/ECTester

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