CVE-2019-3861

An out of bounds read flaw was discovered in libssh2 before 1.8.1 in the way SSH packets with a padding length value greater than the packet length are parsed. A remote attacker who compromises a SSH server may be able to cause a Denial of Service or read data in the client memory.

Published: 2019-03-25 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2019-3861 is rated Moderate Risk (55.5/100): CVSS Medium severity, with high exploitation likelihood (EPSS 5.12%, 91th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +3.58% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize 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-2019-3861

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 1.53% 5.12% +3.58%
2 2026-02-07 1.58% 1.53% -0.04%
3 2026-01-25 — 1.58% —

Full EPSS history (23 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2019-3861

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.0 3.0 MEDIUM
CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L 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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 1.6 3.4 [email protected]
9.1 3.0 CRITICAL
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.2 [email protected]
6.4 2.0 MEDIUM
AV:N/AC:L/Au:N/C:P/I:N/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:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 4.9 [email protected]

Weakness enumeration for CVE-2019-3861

OS Trackers for CVE-2019-3861

vendor priority summary link
alpine critical CVE-2019-3861: 1 source package rows (libssh2); 10 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 10, open 0. https://security.alpinelinux.org/vuln/CVE-2019-3861
debian not yet assigned CVE-2019-3861 not yet assigned priority: Debian including 1 source packages (libssh2), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2019-3861
redhat medium — https://access.redhat.com/security/cve/CVE-2019-3861
suse medium CVE-2019-3861 severity moderate: SUSE including 288 source package names (0.38.1.5.8.40:libssh2-1-1.9.0-4.13.1, 0.38.1.5.8.45:libssh2-1-1.9.0-4.13.1, …), 399 product×package rows across 87 product lines (Container caasp/v4/nginx-ingress-controller, Container suse/sles/15.2/virt-handler, … (87 product lines)): Known Affected 231, Fixed 138, Known Not Affected 30. https://www.suse.com/security/cve/CVE-2019-3861/
ubuntu medium CVE-2019-3861 medium priority: Ubuntu including 1 source packages (libssh2), 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 3, ignored 1, needed 1. https://ubuntu.com/security/CVE-2019-3861

Affected software / configurations for CVE-2019-3861

Vendor Product Version Raw CPE
libssh2 libssh2 >= 0.15, <= 1.8.0 cpe:2.3:a:libssh2:libssh2:*:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
netapp ontap_select_deploy_administration_utility — cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:*
opensuse leap 15.0 cpe:2.3:o:opensuse:leap:15.0:*:*:*:*:*:*:*
opensuse leap 42.3 cpe:2.3:o:opensuse:leap:42.3:*:*:*:*:*:*:*

References for CVE-2019-3861

URL Tags
http://lists.opensuse.org/opensuse-security-announce/2019-03/msg00040.html Mailing List Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00003.html Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:2136
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-3861 Issue Tracking Patch Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/03/msg00032.html Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5DK6VO2CEUTAJFYIKWNZKEKYMYR3NO2O/
https://seclists.org/bugtraq/2019/Apr/25
https://security.netapp.com/advisory/ntap-20190327-0005/ Third Party Advisory
https://www.debian.org/security/2019/dsa-4431
https://www.libssh2.org/CVE-2019-3861.html Patch Vendor Advisory
https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html
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