CVE-2018-9127 — Botan 2.2.0 - 2.4.0 (fixed in 2.5.0) improperly handled wildcard certificates and could accept certain certificates as valid for hostnames when, under RFC 6125 rules, they should not match

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CRITICAL

Botan 2.2.0 - 2.4.0 (fixed in 2.5.0) improperly handled wildcard certificates and could accept certain certificates as valid for hostnames when, under RFC 6125 rules, they should not match

Published Apr 2, 2018

9.8

CRITICAL

CVSS 3.0

EPSS 0.93%

Description

Botan 2.2.0 - 2.4.0 (fixed in 2.5.0) improperly handled wildcard certificates and could accept certain certificates as valid for hostnames when, under RFC 6125 rules, they should not match. This only affects certificates issued to the same domain as the host, so to impersonate a host one must already have a wildcard certificate matching other hosts in the same domain. For example, b*.example.com would match some hostnames that do not begin with a 'b' character.

Affected products

Remediation

No remediation recorded yet.

Metrics

0.93% 0.00930

Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 2, 2026.

EPSS probability 0.00930

Score over time

2021–2026

EPSS v1
EPSS v5
EPSS v2
EPSS v3

Percentile over time

EPSS v1
EPSS v5
EPSS v2
EPSS v3

Table of values (9 key points)

Flat stretches are collapsed; showing up to 120 newest points.

Date	Score	Percentile	Model
Oct 2, 2026	0.93% (0.00930)	59.23th	v5 (v2026.06.15)
Sep 20, 2026	0.93% (0.00930)	59.07th	v5 (v2026.06.15)
Jul 20, 2024	0.15% (0.00150)	51.63th	v3 (v2023.03.01)
Jun 14, 2024	0.15% (0.00150)	51.36th	v3 (v2023.03.01)
Mar 7, 2023	0.15% (0.00150)	49.35th	v3 (v2023.03.01)
Mar 6, 2023	0.89% (0.00885)	27.89th	v2 (v2022.01.01)
Feb 4, 2022	0.89% (0.00885)	10.50th	v2 (v2022.01.01)
Feb 3, 2022	0.42% (0.00416)	10.04th	v5 (v2026.06.15)
Apr 14, 2021	0.42% (0.00416)	0.00th	v1