CVE-2020-17509

ATS negative cache option is vulnerable to a cache poisoning attack. If you have this option enabled, please upgrade or disable this feature. Apache Traffic Server versions 7.0.0 to 7.1.11 and 8.0.0 to 8.1.0 are affected.

Published: 2021-01-11 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-17509 is rated Moderate Risk (55.2/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.79%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-17509

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 3.05% 1.79% -1.25%
2 2025-12-28 1.59% 3.05% +1.45%
3 2025-12-27 — 1.59% —

Full EPSS history (18 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-17509

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2020-17509

OS Trackers for CVE-2020-17509

vendor priority summary link
debian not yet assigned CVE-2020-17509 not yet assigned priority: Debian including 1 source packages (trafficserver), 3 status rows across 3 suites (bookworm, bullseye, sid): resolved 3. https://security-tracker.debian.org/tracker/CVE-2020-17509
ubuntu low CVE-2020-17509 low priority: Ubuntu including 1 source packages (trafficserver), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 10, needed 2, DNE 1, ignored 1, needs-triage 1, released 1. https://ubuntu.com/security/CVE-2020-17509

Affected software / configurations for CVE-2020-17509

Vendor Product Version Raw CPE
apache traffic_server >= 6.0.0, <= 6.2.3 cpe:2.3:a:apache:traffic_server:*:*:*:*:*:*:*:*
apache traffic_server >= 7.0.0, <= 7.1.10 cpe:2.3:a:apache:traffic_server:*:*:*:*:*:*:*:*
apache traffic_server >= 8.0.0, <= 8.0.7 cpe:2.3:a:apache:traffic_server:*:*:*:*:*:*:*:*

References for CVE-2020-17509

cvelogic Threat Intelligence