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Fencer Intel
medium 5.8

CVE-2026-20053 json

Cisco Secure Firewall Threat Defense Software Snort 3 Visual Basic for Application Heap Overflow Denial of Service Vulnerability

published 8mo ago modified 2mo ago also EUVD-2026-9459

cvss
5.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits
0
none known

Summary

Multiple Cisco products are affected by a vulnerability in the Snort 3 VBA feature that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to crash.

This vulnerability is due to improper range checking when decompressing VBA data, which is user controlled. An attacker could exploit this vulnerability by sending crafted VBA data to the Snort 3 Detection Engine on the targeted device. A successful exploit could allow the attacker to cause an overflow of heap data, which could cause a DoS condition.

Patch / fix

  • cisco snort 3.9.3.0

Is CVE-2026-20053 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
8mo ago

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 5.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

Affected products

  • Cisco Cisco Cyber Vision
  • Cisco Cisco Secure Firewall Threat Defense (FTD) Software
  • Cisco Cisco UTD SNORT IPS Engine Software

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.