Is CVE-2019-3859 in the CISA KEV catalog?

No. CVE-2019-3859 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2019-3859?

CVE-2019-3859 has a CVSS v3 base score of 9.1 (CRITICAL).

What is the EPSS score for CVE-2019-3859?

CVE-2019-3859 has an EPSS score of 6.28% (93th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2019-3859?

Upgrade libssh2 on debian 11 to 1.8.0-2.1 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2019-3859

CRITICALEPSS 93th pctl

9.1

CVSS v3

NVD

Description

An out of bounds read flaw was discovered in libssh2 before 1.8.1 in the _libssh2_packet_require and _libssh2_packet_requirev functions. A remote attacker who compromises a SSH server may be able to cause a Denial of Service or read data in the client memory.

CWE-125Out-of-bounds Read

How to fix

Remediation Available

libssh2Debian

Fixed in:1.8.0-2.1CVE-2019-3859

libssh2Ubuntu

Fixed in:1.5.0-2ubuntu0.1+esm1USN-5308-1

libssh2-1Ubuntu

Fixed in:1.5.0-2ubuntu0.1+esm1USN-5308-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Exploit Intelligence

6.28%probability of exploitation in 30 days

93rdpercentile

High risk: more likely to be exploited than 93% of all known CVEs.

References

Patch4

Vendor Advisory1

libssh2.org

Third-Party Advisory11

Other references4

Related Vulnerabilities

Other CWE-125 (Out-of-bounds Read) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2014-0160	High	7.5	100%	KEV	Fix
CVE-2025-5777	High	7.5	100%	KEV + Ransom	Fix
CVE-2021-4034	High	7.8	95%	KEV	Fix
CVE-2023-21769	High	7.5	92%	-	Fix
CVE-2023-49285	High	8.6	89%	-	Fix
CVE-2020-8794	Critical	9.8	89%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-12-18.