Cisco patches 34 flaws, including critical Expressway RCE CVE-2026-76466
Fixes include Expressway X15.5.20 and Snort 3.12.4.0; Cisco says none are known to be exploited.
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CVE-2026-20043
Out-of-bounds write in Cisco open-source Snort 3
- CVSS 3.1
- 9.0 critical
- EPSS
- —
- Published
- ·
- Modified
AI analysisSummaries by Vani AI
Cisco's internal review of open-source Snort 3 found out-of-bounds write flaws (CWE-787), grouped under CVE-2026-20043. A remote attacker can trigger them over the network without credentials or user interaction, though attack complexity is high. Successful exploitation can affect confidentiality, integrity, and availability beyond the vulnerable component. Snort 3 and Cisco products covered by the October 2026 Snort 3 hardening release are affected.
What to do: Apply Cisco's October 2026 Snort 3 security hardening release that addresses CVE-2026-20043. No workaround is named.
| Product | Affected |
|---|---|
| Cisco Open Source Snort 3 | — |
Estimated exposure
No basis for an estimate.
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description · NVD
As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco owned Open Source Snort 3 Software engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20043 are related to issues concerning out-of-bounds writes that are grouped under the Common Weakness Enumeration (CWE) Base CWE-787.
- Weakness
- CWE-787
- Vector
- CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
In the news
2 storiesCisco ships Snort 3 hardening for CVE-2026-20043 out-of-bounds writes
An internal Snort 3 review grouped multiple out-of-bounds write issues, CWE-787, under CVE-2026-20043.
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