No exploitation reportedFix available

CVE-2020-15138

Q: Is CVE-2020-15138 actively exploited?

Active exploitation of CVE-2020-15138 has not been confirmed. Its EPSS score was 2.0% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2020-15138?

CVE-2020-15138 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:L.

No exploitation reported by the sources we read.

Published2020-08-07
Fixed in1.21.0
WeaknessCWE-79

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Prism is vulnerable to Cross-Site Scripting. The easing preview of the Previewers plugin has an XSS vulnerability that allows attackers to execute arbitrary code in Safari and Internet Explorer. This impacts all Safari and Internet Explorer users of Prism >=v1.1.0 that use the _Previewers_ plugin (>=v1.10.0) or the _Previewer: Easing_ plugin (v1.1.0 to v1.9.0). This problem is fixed in version 1.21.0. To workaround the issue without upgrading, disable the easing preview on all impacted code blocks. You need Prism v1.10.0 or newer to apply this workaround.

Timeline

dates in UTC

2020-08-0717:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-15138?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-15138?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Prismjs previewersversion to verify

Branch	Affected	Fixed in	Source
1.x	≥ 1.1.0, < 1.21.0	1.21.0	NVD · OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Prismjs previewers to 1.21.0

Advisories and patches

github.comPatch
prismjs.comVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CNACVSS 3.17.1read 2026-10-23
NVDCVSS 3.17.5read 2026-10-23
NVDCVSS 2.02.6read 2026-10-23
CNAweakness (CWE)CWE-79read 2026-10-23
NVDweakness (CWE)CWE-79read 2026-10-23
FIRST EPSSEPSS score2.0 %2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:L
Published: 2020-08-07
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2020-15138?

Is CVE-2020-15138 actively exploited?

Active exploitation of CVE-2020-15138 has not been confirmed. Its EPSS score was 2.0% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-15138?

CVE-2020-15138 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:L.

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