# CVE-2026-63448: Suricata SMB parser unbounded transaction accumulation DoS

Source: https://junglewise.ai/threats/cve-2026-63448-suricata-is-a-network-intrusion-detection-system-intrusion  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-18. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-63448 · Severity: medium · CVSS 5.9 · Published 2026-09-18

Suricata is a network security monitoring and intrusion detection system that inspects network traffic for threats. A flaw in its SMB protocol parser allows an attacker to send sustained one-directional SMB traffic that causes unbounded accumulation of transaction state in memory and CPU, exhausting server resources and disrupting network monitoring capability.

Technologies: [OISF Suricata](https://junglewise.ai/threats/technologies/suricata). Vendors: [OISF](https://junglewise.ai/threats/vendors/oisf).

## Quick answers

**Is CVE-2026-63448 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-63448 being exploited in the wild.

**How severe is CVE-2026-63448?** Medium severity, with a CVSS score of 5.9, published 18 September 2026.

**Which products and versions are affected?** OISF Suricata prior to 7.0.17 and 8.0.6.

**Is there a fix for CVE-2026-63448?** A patch was published on 2026-07-01: Fix committed to main branch Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-63448 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-63448?** Check whether you run OISF Suricata 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

The SMB parser in Suricata's Rust codebase fails to properly enforce the SMB_MAX_TX transaction limit on asymmetric flows where payload is observed in only one direction, including async-oneside flows. The transaction cleanup mechanism waits for inspection in the unseen direction, allowing transactions to accumulate without bound. An attacker sending sustained one-directional SMB traffic can exhaust CPU and memory resources on the monitored system.

## Affected products

- OISF Suricata prior to 7.0.17 and 8.0.6

## Timeline

- 2026-09-18: disclosed: CVE-2026-63448 published
- 2026-07-01: patched: Fix committed to main branch
- 2026-07-07: patched: Fix available in versions 7.0.17 and 8.0.6

## References

- [https://github.com/OISF/suricata/commit/755d6c3061de4d7ba97f0ed31cdc17ab8cab4476](https://github.com/OISF/suricata/commit/755d6c3061de4d7ba97f0ed31cdc17ab8cab4476)
- [https://github.com/OISF/suricata/commit/7ec9d72d28b9370712cf77a5b9d40d6b5db27cb4](https://github.com/OISF/suricata/commit/7ec9d72d28b9370712cf77a5b9d40d6b5db27cb4)

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- [Suricata DoH2 type confusion in HTTP state cleanup](https://junglewise.ai/threats/cve-2026-94083-suricata-before-8-0-7-has-a-doh2-type-confusion-that-can-cause-an)
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