CVE-2019-9894

A remotely triggerable memory overwrite in RSA key exchange in PuTTY before 0.71 can occur before host key verification.

Published: 2019-03-21 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2019-9894 is rated Moderate Risk (54.7/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.66%). 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-2019-9894

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 2026-05-27 0.94% 0.66% -0.28%
2 2025-11-21 0.98% 0.94% -0.04%
3 2025-11-18 — 0.98% —

Full EPSS history (18 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2019-9894

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.0 HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N 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:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
6.4 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/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:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 4.9 [email protected]

Weakness enumeration for CVE-2019-9894

OS Trackers for CVE-2019-9894

vendor priority summary link
alpine high CVE-2019-9894: 1 source package rows (putty); 11 state rows across 11 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-community, 3.21-community, 3.22-community, edge-community, edge-main); fixed 11, open 0. https://security.alpinelinux.org/vuln/CVE-2019-9894
debian not yet assigned CVE-2019-9894 not yet assigned priority: Debian including 1 source packages (putty), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2019-9894
ubuntu medium CVE-2019-9894 medium priority: Ubuntu including 1 source packages (putty), 19 status rows across 19 suites (bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 14, released 2, DNE 1, ignored 1, needs-triage 1. https://ubuntu.com/security/CVE-2019-9894

Affected software / configurations for CVE-2019-9894

Vendor Product Version Raw CPE
putty putty < 0.71 cpe:2.3:a:putty:putty:*:*:*:*:*:*:*:*
fedoraproject fedora 28 cpe:2.3:o:fedoraproject:fedora:28:*:*:*:*:*:*:*
fedoraproject fedora 29 cpe:2.3:o:fedoraproject:fedora:29:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
netapp oncommand_unified_manager — cpe:2.3:a:netapp:oncommand_unified_manager:-:*:*:*:*:*:*:*
opensuse leap 15.0 cpe:2.3:o:opensuse:leap:15.0:*:*:*:*:*:*:*

References for CVE-2019-9894

URL Tags
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00004.html Mailing List Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00020.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/04/msg00023.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/36LWQ3NPFIV7DC7TC4KFPRYRH2OR7SZ2/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LDO3F267P347E6U2IILFCYW7JPTLCCES/
https://seclists.org/bugtraq/2019/Apr/6 Mailing List Third Party Advisory
https://security.netapp.com/advisory/ntap-20190404-0001/ Patch Third Party Advisory
https://www.chiark.greenend.org.uk/~sgtatham/putty/changes.html Third Party Advisory
https://www.debian.org/security/2019/dsa-4423 Third Party Advisory
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