CVE-2020-9498

Apache Guacamole 1.1.0 and older may mishandle pointers involved inprocessing data received via RDP static virtual channels. If a userconnects to a malicious or compromised RDP server, a series ofspecially-crafted PDUs could result in memory corruption, possiblyallowing arbitrary code to be executed with the privileges of therunning guacd process.

Published: 2020-07-02 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-9498 is rated Moderate Risk (44.8/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.74%). 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-2020-9498

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 0.11% 0.74% +0.63%
2 2025-11-21 0.17% 0.11% -0.07%
3 2025-11-18 — 0.17% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-9498

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.7 3.1 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.8 5.9 [email protected]
6.2 2.0 MEDIUM
AV:L/AC:H/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:H)
Exploitation requires uncommon or highly specific conditions.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 1.9 10.0 [email protected]

Weakness enumeration for CVE-2020-9498

OS Trackers for CVE-2020-9498

vendor priority summary link
debian not yet assigned CVE-2020-9498 not yet assigned priority: Debian including 1 source packages (guacamole-server), 1 status rows across 1 suites (bullseye): resolved 1. https://security-tracker.debian.org/tracker/CVE-2020-9498
ubuntu low CVE-2020-9498 low priority: Ubuntu including 1 source packages (guacamole-client), 17 status rows across 17 suites (bionic, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 14, needs-triage 3. https://ubuntu.com/security/CVE-2020-9498

Affected software / configurations for CVE-2020-9498

Vendor Product Version Raw CPE
apache guacamole <= 1.1.0 cpe:2.3:a:apache:guacamole:*:*:*:*:*:*:*:*
fedoraproject fedora 32 cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

References for CVE-2020-9498

URL Tags
https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44525 Third Party Advisory
https://lists.apache.org/thread.html/r1125f3044a0946d1e7e6f125a6170b58d413ebd4a95157e4608041c7%40%3Cannounce.apache.org%3E
https://lists.apache.org/thread.html/r26fb170edebff842c74aacdb1333c1338f0e19e5ec7854d72e4680fc%40%3Cannounce.apache.org%3E
https://lists.apache.org/thread.html/r90890afea72a9571d666820b2fe5942a0a5f86be406fa31da3dd0922%40%3Cannounce.apache.org%3E
https://lists.apache.org/thread.html/rff824b38ebd2fddc726b816f0e509696b83b9f78979d0cd021ca623b%40%3Cannounce.guacamole.apache.org%3E Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/11/msg00010.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TVV5K2X4EXSAVUUL7IJ3MUJ3ADWMVSBM/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WNS7UHBOFV6JHWH5XOEZTE3BREGRSSQ3/
https://research.checkpoint.com/2020/apache-guacamole-rce/ Third Party Advisory
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