CVE-2019-17498
📋 TL;DR
CVE-2019-17498 is an integer overflow vulnerability in libssh2 v1.9.0 and earlier that allows a malicious SSH server to read arbitrary memory from a client system during connection. This can lead to sensitive information disclosure or denial of service when users connect to compromised servers. Any application using vulnerable libssh2 versions as an SSH client is affected.
💻 Affected Systems
- libssh2
- applications using libssh2 library
📦 What is this software?
Fedora by Fedoraproject
Fedora by Fedoraproject
Leap by Opensuse
Libssh2 by Libssh2
Ontap Select Deploy Administration Utility by Netapp
View all CVEs affecting Ontap Select Deploy Administration Utility →
Solidfire by Netapp
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution or complete system compromise through memory corruption leading to arbitrary code execution.
Likely Case
Information disclosure of sensitive memory contents (passwords, keys, session data) or denial of service through application crash.
If Mitigated
Limited impact with proper network segmentation and trusted server connections only.
🎯 Exploit Status
Exploitation requires a malicious SSH server that a client connects to. Public proof-of-concept code exists in GitHub repositories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: libssh2 v1.9.1 and later
Vendor Advisory: https://www.libssh2.org/
Restart Required: Yes
Instructions:
1. Update libssh2 to version 1.9.1 or later. 2. Rebuild or restart applications using libssh2. 3. For package-managed systems: use 'apt upgrade libssh2-1' (Debian/Ubuntu) or 'yum update libssh2' (RHEL/CentOS).
🔧 Temporary Workarounds
Restrict SSH connections
allOnly allow SSH connections to trusted, verified servers
Network segmentation
allIsolate systems using libssh2 from untrusted networks
🧯 If You Can't Patch
- Implement strict outbound firewall rules to only allow SSH connections to trusted servers
- Monitor for abnormal SSH client behavior and connection attempts to unknown servers
🔍 How to Verify
Check if Vulnerable:
Check libssh2 version: 'ldconfig -p | grep libssh2' or 'dpkg -l | grep libssh2' on Debian/Ubuntu, 'rpm -qa | grep libssh2' on RHEL/CentOSCheck Version:
pkg-config --modversion libssh2 || strings /usr/lib/libssh2.so | grep 'libssh2'Verify Fix Applied:
Verify libssh2 version is 1.9.1 or higher using version check commands📡 Detection & Monitoring
Log Indicators:
- SSH client crashes
- Abnormal memory access patterns in application logs
- Failed SSH connections with unusual error codes
Network Indicators:
- SSH connections to unknown or suspicious servers
- Unusual SSH traffic patterns from clients
SIEM Query:
source="ssh" AND (event_type="crash" OR error_code="*overflow*")🔗 References
- http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00026.html
- http://packetstormsecurity.com/files/172835/libssh2-1.9.0-Out-Of-Bounds-Read.html
- https://blog.semmle.com/libssh2-integer-overflow-CVE-2019-17498/
- https://github.com/kevinbackhouse/SecurityExploits/tree/8cbdbbe6363510f7d9ceec685373da12e6fc752d/libssh2/out_of_bounds_read_disconnect_CVE-2019-17498
- https://github.com/libssh2/libssh2/blob/42d37aa63129a1b2644bf6495198923534322d64/src/packet.c#L480
- https://github.com/libssh2/libssh2/commit/dedcbd106f8e52d5586b0205bc7677e4c9868f9c
- https://lists.debian.org/debian-lts-announce/2019/11/msg00010.html
- https://lists.debian.org/debian-lts-announce/2021/12/msg00013.html
- https://lists.debian.org/debian-lts-announce/2023/09/msg00006.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22H4Q5XMGS3QNSA7OCL3U7UQZ4NXMR5O/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TY7EEE34RFKCTXTMBQQWWSLXZWSCXNDB/
- https://security.netapp.com/advisory/ntap-20220909-0004/
- http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00026.html
- http://packetstormsecurity.com/files/172835/libssh2-1.9.0-Out-Of-Bounds-Read.html
- https://blog.semmle.com/libssh2-integer-overflow-CVE-2019-17498/
- https://github.com/kevinbackhouse/SecurityExploits/tree/8cbdbbe6363510f7d9ceec685373da12e6fc752d/libssh2/out_of_bounds_read_disconnect_CVE-2019-17498
- https://github.com/libssh2/libssh2/blob/42d37aa63129a1b2644bf6495198923534322d64/src/packet.c#L480
- https://github.com/libssh2/libssh2/commit/dedcbd106f8e52d5586b0205bc7677e4c9868f9c
- https://lists.debian.org/debian-lts-announce/2019/11/msg00010.html
- https://lists.debian.org/debian-lts-announce/2021/12/msg00013.html
- https://lists.debian.org/debian-lts-announce/2023/09/msg00006.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22H4Q5XMGS3QNSA7OCL3U7UQZ4NXMR5O/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TY7EEE34RFKCTXTMBQQWWSLXZWSCXNDB/
- https://security.netapp.com/advisory/ntap-20220909-0004/
