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. 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.

Published: 2018-04-02 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-9127 is rated Moderate Risk (59.9/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 0.96%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2018-9127

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.19% 0.96% +0.78%
2 2025-03-30 0.65% 0.19% -0.46%
3 2025-03-29 — 0.65% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-9127

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.0 CRITICAL
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2018-9127

OS Trackers for CVE-2018-9127

vendor priority summary link
alpine critical CVE-2018-9127: 1 source package rows (botan); 8 state rows across 8 repos (3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, edge-main); fixed 8, open 0. https://security.alpinelinux.org/vuln/CVE-2018-9127
debian not yet assigned CVE-2018-9127 not yet assigned priority: Debian including 1 source packages (botan), 3 status rows across 3 suites (bookworm, bullseye, trixie): resolved 3. https://security-tracker.debian.org/tracker/CVE-2018-9127
ubuntu medium CVE-2018-9127 medium priority: Ubuntu including 1 source packages (botan), 20 status rows across 20 suites (artful, bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 7, not-affected 7, DNE 3, needs-triage 2, released 1. https://ubuntu.com/security/CVE-2018-9127

Affected software / configurations for CVE-2018-9127

Vendor Product Version Raw CPE
botan_project botan >= 2.2.0, <= 2.4.0 cpe:2.3:a:botan_project:botan:*:*:*:*:*:*:*:*

References for CVE-2018-9127

URL Tags
https://botan.randombit.net/security.html Third Party Advisory
cvelogic Threat Intelligence