CVE-2020-13998: citrix xenapp Observable Discrepancy
CVSS: 7.5v3.1HighModified
Published 11-06-2020Last modified 04-08-2024
Vulnerability summary
CVE-2020-13998 is a high (CVSS 7.5) Observable Discrepancy vulnerability in citrix xenapp. EPSS estimates a 1.39% chance of exploitation in the next 30 days, higher than 71.8% of scored vulnerabilities.
CVSS score
7.5/10
010
High · v3.1 (CVE.org)EPSS score
1.39%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Timeline
- 11-06-2020PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
Description
Citrix XenApp 6.5, when 2FA is enabled, allows a remote unauthenticated attacker to ascertain whether a user exists on the server, because the 2FA error page only occurs after a valid username is entered. NOTE: This vulnerability only affects products that are no longer supported by the maintainer
CVSS metrics
3 scores · 2 sources · 2 versionsHigh 7.5Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NSources2 sources · 5.3–7.5
- NVDNIST5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NDiffers
Medium 4.3Preferred score · NVD (NIST)
AV:N/AC:M/Au:N/C:P/I:N/A:NSourcesSingle source
EPSS trend
Probability
1.39%
Chance of exploitation in the next 30 days
Percentile
72%
Versus all other CVEs
30-day change
0.00 pp
From 1.39% on 18-09-2026
18-09-202618-10-2026
EPSS score1.39%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-203Observable DiscrepancyThe product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.
- CWE-639Authorization Bypass Through User-Controlled KeyThe system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
Affected systems
Citrix1 product
- xenapp6.5.0.0
1 vendor · 1 product