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Fencer Vulns
high 7.5

CVE-2019-3855 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 packets are read from…

published 2019-03-21 7 y ago modified 2026-10-14 25 d ago also EUVD-2019-13469

cvss
7.5
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
9.3%
EPSS 9.3% chance of exploitation in 30 days, percentile 95%
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 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.

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-2019-3855

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

ubuntu advisories UBUNTU-CVE-2019-3855

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-2019-3855

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-2019-3855 updated cvss 7.5

libssh2: Integer overflow in transport read 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
10 mo ago

Exploit prediction

9.29% chance of exploitation in the next 30 days, higher than 95% 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 9.3 AV:N/AC:M/Au:N/C:C/I:C/A:C

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.