# CVE-2026-59848: libssh denial of service via memory exhaustion in SFTP client

Source: https://junglewise.ai/threats/cve-2026-59848-libssh-denial-of-service-via-memory-exhaustion-in-sftp-client  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-21. Updated: 2026-07-21  
License: CC BY 4.0 with a link back

CVE-2026-59848 · Severity: medium · CVSS 5.3 · Published 2026-07-21

A vulnerability in the libssh library allows a malicious file server to crash client applications. When a user connects to a compromised or malicious SFTP server, the server can flood the client with fake data responses that the client stores indefinitely. This leads to the client application consuming all available memory, resulting in a system crash or service outage.

Technologies: [Libssh](https://junglewise.ai/threats/technologies/libssh), [Red Hat Enterprise Linux 10](https://junglewise.ai/threats/technologies/enterprise-linux-10), [Red Hat Enterprise Linux 8](https://junglewise.ai/threats/technologies/enterprise-linux-8), [Red Hat Enterprise Linux 9](https://junglewise.ai/threats/technologies/enterprise-linux-9). Vendors: [Libssh](https://junglewise.ai/threats/vendors/libssh), [Red Hat](https://junglewise.ai/threats/vendors/red-hat).

## Quick answers

**Is CVE-2026-59848 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-59848 being exploited in the wild.

**How severe is CVE-2026-59848?** Medium severity, with a CVSS score of 5.3, published 21 July 2026.

**Which products and versions are affected?** Red Hat Enterprise Linux 10 affected; Red Hat Enterprise Linux 8 affected; Red Hat Enterprise Linux 9 affected.

**Is there a fix for CVE-2026-59848?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-59848 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-59848?** Check whether you run Libssh, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8 or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A flaw was discovered in the libssh client-side SFTP message handling within the 'sftp_get_message()' function in 'src/sftp_common.c'. The library fails to validate request IDs in incoming SFTP responses, allowing responses for IDs that were never issued by the client to be accepted and queued. A malicious SFTP server can exploit this by repeatedly sending responses with unknown IDs, leading to unbounded memory consumption. This results in a client-side denial of service (DoS) via memory exhaustion. The attack requires a client to connect to a malicious or compromised server.

## Affected products

- libssh libssh
- Red Hat Red Hat Enterprise Linux 8 affected
- Red Hat Red Hat Enterprise Linux 9 affected
- Red Hat Red Hat Enterprise Linux 10 affected
- Red Hat Red Hat Hardened Images affected

## Timeline

- 2026-07-08: disclosed: Initial report in Red Hat Bugzilla
- 2026-07-21: advisory: CVE published and NVD record created

## References

- [https://access.redhat.com/downloads/content/package-browser/](https://access.redhat.com/downloads/content/package-browser/)
- [https://access.redhat.com/security/cve/CVE-2026-59848](https://access.redhat.com/security/cve/CVE-2026-59848)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2498181](https://bugzilla.redhat.com/show_bug.cgi?id=2498181)

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