CVE-2019-3855

CVE-2019-3855 is a high-severity vulnerability in Redhat Enterprise Linux with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-190.

Key facts

• Severity: High (CVSS 3.x base score 8.8)
• CVSS v2: 9.3
• EPSS exploit prediction: 9% (95th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-190
• Affected product: Redhat Enterprise Linux
• Published: 2019-03-21
• Last modified: 2026-06-17

Description

An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2 before 1.8.1 in the way packets are read from the server. A remote attacker who compromises a SSH server may be able to execute code on the client system when a user connects to the server.

Frequently asked questions

What is CVE-2019-3855?

An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2 before 1.8.1 in the way packets are read from the server. A remote attacker who compromises a SSH server may be able to execute code on the client system when a user connects to the server.

How severe is CVE-2019-3855?

CVE-2019-3855 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2019-3855 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 9% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-3855?

CVE-2019-3855 primarily affects Redhat Enterprise Linux. In total, 18 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-3855?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2019-3855 published?

CVE-2019-3855 was published on 2019-03-21 and last updated on 2026-06-17.

References

• http://lists.opensuse.org/opensuse-security-announce/2019-03/msg00040.html
• http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00003.html
• http://packetstormsecurity.com/files/152136/Slackware-Security-Advisory-libssh2-Updates.html
• http://seclists.org/fulldisclosure/2019/Sep/42
• http://www.openwall.com/lists/oss-security/2019/03/18/3
• http://www.securityfocus.com/bid/107485
• https://access.redhat.com/errata/RHSA-2019:0679
• https://access.redhat.com/errata/RHSA-2019:1175
• https://access.redhat.com/errata/RHSA-2019:1652
• https://access.redhat.com/errata/RHSA-2019:1791
• https://access.redhat.com/errata/RHSA-2019:1943
• https://access.redhat.com/errata/RHSA-2019:2399
• https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-3855
• https://lists.debian.org/debian-lts-announce/2019/03/msg00032.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5DK6VO2CEUTAJFYIKWNZKEKYMYR3NO2O/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6LUNHPW64IGCASZ4JQ2J5KDXNZN53DWW/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M7IF3LNHOA75O4WZWIHJLIRMA5LJUED3/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XCWEA5ZCLKRDUK62QVVYMFWLWKOPX3LO/
• https://seclists.org/bugtraq/2019/Apr/25
• https://seclists.org/bugtraq/2019/Mar/25
• https://seclists.org/bugtraq/2019/Sep/49
• https://security.netapp.com/advisory/ntap-20190327-0005/
• https://support.apple.com/kb/HT210609
• https://www.broadcom.com/support/fibre-channel-networking/security-advisories/brocade-security-advisory-2019-767
• https://www.debian.org/security/2019/dsa-4431
• https://www.libssh2.org/CVE-2019-3855.html
• https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html

Affected products (18)

• cpe:2.3:a:libssh2:libssh2:*:*:*:*:*:*:*:*
• cpe:2.3:o:fedoraproject:fedora:28:*:*:*:*:*:*:*
• cpe:2.3:o:fedoraproject:fedora:29:*:*:*:*:*:*:*
• cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
• cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:advanced_virtualization:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_desktop:7.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server:7.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_aus:7.6:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_eus:7.6:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_tus:7.6:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_workstation:7.0:*:*:*:*:*:*:*
• cpe:2.3:o:opensuse:leap:42.3:*:*:*:*:*:*:*
• cpe:2.3:a:apple:xcode:*:*:*:*:*:*:*:*
• cpe:2.3:a:oracle:peoplesoft_enterprise_peopletools:8.56:*:*:*:*:*:*:*
• cpe:2.3:a:oracle:peoplesoft_enterprise_peopletools:8.57:*:*:*:*:*:*:*

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