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Fencer Vulns
high 7.5

CVE-2019-3856 json

An integer overflow flaw, which could lead to an out of bounds write, was discovered in libssh2 before 1.8.1 in the way keyboard prompt req…

published 2019-03-25 7 y ago modified 2026-10-14 25 d ago also EUVD-2019-13470

cvss
7.5
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
6.1%
EPSS 6.1% chance of exploitation in 30 days, percentile 93%
public exploits
0
none known

Summary

An integer overflow flaw, which could lead to an out of bounds write, was discovered in libssh2 before 1.8.1 in the way keyboard prompt requests are parsed. 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.

Patch / fix

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • libssh2 Debian 14, Debian 13, Debian 12 1.8.0-2.1

debian advisories DEBIAN-CVE-2019-3856

  • libssh2 Ubuntu Pro 14.04 LTS 1.4.3-2ubuntu0.2+esm2
  • libssh2 Ubuntu Pro 16.04 LTS 1.5.0-2ubuntu0.1+esm1

ubuntu advisories UBUNTU-CVE-2019-3856

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • SLOF RHEL 8 20171214-5.gitfa98132.module+el8.0.0+3075+09be6b65
  • hivex RHEL 8 1.3.15-6.module+el8.0.0+3075+09be6b65
  • netcf RHEL 8 0.2.8-10.module+el8.0.0+3075+09be6b65
  • nbdkit RHEL 8 1.4.2-4.module+el8.0.0+3075+09be6b65
  • libssh2 RHEL 8 1.8.0-7.module+el8.0.0+3075+09be6b65.1
  • libvirt RHEL 8 4.5.0-23.1.module+el8.0.0+3151+3ba813f9
  • seabios RHEL 8 1.11.1-3.module+el8.0.0+3075+09be6b65
  • sgabios RHEL 8 1:0.20170427git-2.module+el8.0.0+3075+09be6b65

red hat advisories RHSA-2019:1175RHSA-2019:2399RHSA-2019:1943RHSA-2019:1652RHSA-2019:1791RHSA-2019:0679

  • libssh2_org SLES for SAP 15, SLES 15-LTSS, SLE Module for Basesystem 15 SP2 +3 more 1.9.0-4.13.1
  • libssh2_org SLE Point of Sale 11 SP3 1.2.9-4.2.12.5.1
  • libssh2_org SLES for SAP 12 SP4, SLES for SAP 12 SP3, SLES for SAP 12 SP2 +13 more 1.4.3-20.3.1
  • libssh2_org SLES for SAP 11 SP4, SLES 11 SP4, SLE Software Development Kit 11 SP4 1.4.3-17.3.1

suse advisories SUSE-SU-2020:3551-1SUSE-SU-2019:13997-1SUSE-SU-2019:0655-1SUSE-SU-2019:13982-1

  • libssh2_org openSUSE Tumbleweed 1.9.0-3.6
  • libssh2_org openSUSE Leap 15.2 1.9.0-lp152.8.3.1
  • libssh2_org openSUSE Leap 15.1 1.9.0-lp151.6.6.1
  • libssh2_org openSUSE Leap 15.0 1.8.0-lp150.3.3.1

opensuse advisories openSUSE-SU-2024:10999-1openSUSE-SU-2020:2129-1openSUSE-SU-2020:2126-1openSUSE-SU-2019:1109-1

  • libssh2 Alpine 3.24, Alpine 3.23, Alpine 3.22 +13 more 1.8.1-r0

alpine advisories ALPINE-CVE-2019-3856

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libssh2 Arch Linux 1.8.1-1

arch linux advisories AVG-926

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-3856 updated cvss 7.5

libssh2: Integer overflow in keyboard interactive handling resulting in out of bounds write

  • Red Hat Enterprise Linux 8 Advanced Virtualization libssh2
    affected: no fix available
  • Red Hat Virtualization 4 rhvm-appliance, redhat-virtualization-host-image-update
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux AppStream (v. 8) hivex 1.3.15-6.module+el8.0.0+3075+09be6b65, nbdkit 1.4.2-4.module+el8.0.0+3075+09be6b65, netcf 0.2.8-10.module+el8.0.0+3075+09be6b65, seabios 1.11.1-3.module+el8.0.0+3075+09be6b65, libiscsi 1.18.0-6.module+el8.0.0+3075+09be6b65, libssh2 1.8.0-7.module+el8.0.0+3075+09be6b65.1, +82 more
    fixed: vendor fix RHSA-2019:1175
  • Red Hat Enterprise Linux Client (v. 7) libssh2 1.4.3-12.el7_6.2 Red Hat Enterprise Linux Client Optional (v. 7) libssh2-docs 1.4.3-12.el7_6.2, libssh2-devel 1.4.3-12.el7_6.2, libssh2-debuginfo 1.4.3-12.el7_6.2 Red Hat Enterprise Linux ComputeNode (v. 7) libssh2 1.4.3-12.el7_6.2
    fixed: vendor fix RHSA-2019:0679
  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.4) libssh2 1.4.3-11.el7_4.1
    fixed: vendor fix RHSA-2019:1943
  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.5) libssh2 1.4.3-11.el7_5.1
    fixed: vendor fix RHSA-2019:1791
  • Red Hat Enterprise Linux ComputeNode Optional (v. 7) libssh2-docs 1.4.3-12.el7_6.2, libssh2-devel 1.4.3-12.el7_6.2, libssh2-debuginfo 1.4.3-12.el7_6.2
    fixed: vendor fix RHSA-2019:0679
  • Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.4) libssh2-docs 1.4.3-11.el7_4.1, libssh2-devel 1.4.3-11.el7_4.1, libssh2-debuginfo 1.4.3-11.el7_4.1
    fixed: vendor fix RHSA-2019:1943
show 18 more
  • Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.5) libssh2-docs 1.4.3-11.el7_5.1, libssh2-devel 1.4.3-11.el7_5.1, libssh2-debuginfo 1.4.3-11.el7_5.1
    fixed: vendor fix RHSA-2019:1791
  • Red Hat Enterprise Linux Desktop (v. 6) libssh2 1.4.2-3.el6_10.1 Red Hat Enterprise Linux Desktop Optional (v. 6) libssh2-docs 1.4.2-3.el6_10.1, libssh2-devel 1.4.2-3.el6_10.1, libssh2-debuginfo 1.4.2-3.el6_10.1
    fixed: vendor fix RHSA-2019:1652
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) libssh2 1.4.3-12.el7_6.2 Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) libssh2-docs 1.4.3-12.el7_6.2, libssh2-devel 1.4.3-12.el7_6.2, libssh2-debuginfo 1.4.3-12.el7_6.2
    fixed: vendor fix RHSA-2019:0679
  • Red Hat Enterprise Linux HPC Node (v. 6) libssh2 1.4.2-3.el6_10.1 Red Hat Enterprise Linux HPC Node Optional (v. 6) libssh2-docs 1.4.2-3.el6_10.1, libssh2-devel 1.4.2-3.el6_10.1, libssh2-debuginfo 1.4.2-3.el6_10.1 Red Hat Enterprise Linux Server (v. 6) libssh2 1.4.2-3.el6_10.1
    fixed: vendor fix RHSA-2019:1652
  • Red Hat Enterprise Linux Server (v. 7) libssh2 1.4.3-12.el7_6.2
    fixed: vendor fix RHSA-2019:0679
  • Red Hat Enterprise Linux Server AUS (v. 7.3) libssh2 1.4.3-11.el7_3.1 Red Hat Enterprise Linux Server E4S (v. 7.3) libssh2 1.4.3-11.el7_3.1
    fixed: vendor fix RHSA-2019:2399
  • Red Hat Enterprise Linux Server EUS (v. 7.4) libssh2 1.4.3-11.el7_4.1
    fixed: vendor fix RHSA-2019:1943
  • Red Hat Enterprise Linux Server EUS (v. 7.5) libssh2 1.4.3-11.el7_5.1
    fixed: vendor fix RHSA-2019:1791
  • Red Hat Enterprise Linux Server Optional (v. 6) libssh2-docs 1.4.2-3.el6_10.1, libssh2-devel 1.4.2-3.el6_10.1, libssh2-debuginfo 1.4.2-3.el6_10.1
    fixed: vendor fix RHSA-2019:1652
  • Red Hat Enterprise Linux Server Optional (v. 7) libssh2-docs 1.4.3-12.el7_6.2, libssh2-devel 1.4.3-12.el7_6.2, libssh2-debuginfo 1.4.3-12.el7_6.2
    fixed: vendor fix RHSA-2019:0679
  • Red Hat Enterprise Linux Server Optional AUS (v. 7.3) libssh2-docs 1.4.3-11.el7_3.1, libssh2-devel 1.4.3-11.el7_3.1, libssh2-debuginfo 1.4.3-11.el7_3.1 Red Hat Enterprise Linux Server Optional E4S (v. 7.3) libssh2-docs 1.4.3-11.el7_3.1, libssh2-devel 1.4.3-11.el7_3.1, libssh2-debuginfo 1.4.3-11.el7_3.1
    fixed: vendor fix RHSA-2019:2399
  • Red Hat Enterprise Linux Server Optional EUS (v. 7.4) libssh2-docs 1.4.3-11.el7_4.1, libssh2-devel 1.4.3-11.el7_4.1, libssh2-debuginfo 1.4.3-11.el7_4.1
    fixed: vendor fix RHSA-2019:1943
  • Red Hat Enterprise Linux Server Optional EUS (v. 7.5) libssh2-docs 1.4.3-11.el7_5.1, libssh2-devel 1.4.3-11.el7_5.1, libssh2-debuginfo 1.4.3-11.el7_5.1
    fixed: vendor fix RHSA-2019:1791
  • Red Hat Enterprise Linux Server Optional TUS (v. 7.3) libssh2-docs 1.4.3-11.el7_3.1, libssh2-devel 1.4.3-11.el7_3.1, libssh2-debuginfo 1.4.3-11.el7_3.1 Red Hat Enterprise Linux Server TUS (v. 7.3) libssh2 1.4.3-11.el7_3.1
    fixed: vendor fix RHSA-2019:2399
  • Red Hat Enterprise Linux Workstation (v. 6) libssh2 1.4.2-3.el6_10.1
    fixed: vendor fix RHSA-2019:1652
  • Red Hat Enterprise Linux Workstation (v. 7) libssh2 1.4.3-12.el7_6.2
    fixed: vendor fix RHSA-2019:0679
  • Red Hat Enterprise Linux Workstation Optional (v. 6) libssh2-docs 1.4.2-3.el6_10.1, libssh2-devel 1.4.2-3.el6_10.1, libssh2-debuginfo 1.4.2-3.el6_10.1
    fixed: vendor fix RHSA-2019:1652
  • Red Hat Enterprise Linux Workstation Optional (v. 7) libssh2-docs 1.4.3-12.el7_6.2, libssh2-devel 1.4.3-12.el7_6.2, libssh2-debuginfo 1.4.3-12.el7_6.2
    fixed: vendor fix RHSA-2019:0679

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-23-348-10 updated cvss 8.8

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
18 mo ago

Exploit prediction

6.13% chance of exploitation in the next 30 days, higher than 93% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.0 7.5 CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • The libssh2 Project libssh2
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.