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Vulnerability DatabaseCVE-2020-17509

CVE-2020-17509: 
Apache Traffic Server vulnerability analysis and mitigation

Overview

Apache Traffic Server (ATS) negative cache option was identified as vulnerable to a cache poisoning attack, affecting versions 7.0.0 to 7.1.11 and 8.0.0 to 8.1.0. The vulnerability was assigned CVE-2020-17509 and was publicly disclosed on January 11, 2021 (NVD).

Technical details

The vulnerability received a CVSS v3.1 base score of 7.5 (HIGH) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N, indicating a network-accessible vulnerability requiring no privileges or user interaction to exploit. The vulnerability is classified under CWE-444 (Inconsistent Interpretation of HTTP Requests) (NVD).

Impact

The vulnerability allows attackers to perform cache poisoning attacks when the negative cache option is enabled. This could lead to high impact on integrity while not affecting confidentiality or availability of the system (NVD).

Exploitability

The vulnerability is network accessible (AV:N) with low attack complexity (AC:L), requiring no privileges (PR:N) or user interaction (UI:N) to exploit (NVD).

Mitigation and workarounds

Users are advised to either upgrade to a patched version of Apache Traffic Server or disable the negative cache feature if an immediate upgrade is not possible (Debian Security).

Additional resources

Source: This report was generated using AI

Related Apache Traffic Server vulnerabilities:

CVE ID

Severity

Score

Technologies

Component name

CISA KEV exploit

Has fix

Published date

CVE-2026-58188HIGH8.4
  • Apache Traffic Server logoApache Traffic Server
  • trafficserver9
NoYesJul 29, 2026
CVE-2026-58189HIGH8.2
  • Apache Traffic Server logoApache Traffic Server
  • trafficserver-debugsource
NoYesJul 29, 2026
CVE-2026-58186HIGH8.2
  • Apache Traffic Server logoApache Traffic Server
  • trafficserver-devel
NoYesJul 29, 2026
CVE-2026-65100MEDIUM6.3
  • Apache Traffic Server logoApache Traffic Server
  • trafficserver-debuginfo
NoYesJul 29, 2026
CVE-2026-58187MEDIUM6.3
  • Apache Traffic Server logoApache Traffic Server
  • trafficserver-devel
NoYesJul 29, 2026

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