No exploitation reportedFix available

CVE-2020-25817

Q: Is CVE-2020-25817 actively exploited?

Active exploitation of CVE-2020-25817 has not been confirmed. Its EPSS score was 0.8% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2020-25817?

CVE-2020-25817 has a CVSS v3 base score of 4.8 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N.

No exploitation reported by the sources we read.

Published2021-06-08
Fixed in4.6.0
WeaknessCWE-611

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

SilverStripe through 4.6.0-rc1 has an XXE Vulnerability in CSSContentParser. A developer utility meant for parsing HTML within unit tests can be vulnerable to XML External Entity (XXE) attacks. When this developer utility is misused for purposes involving external or user submitted data in custom project code, it can lead to vulnerabilities such as XSS on HTML output rendered through this custom code. This is now mitigated by disabling external entities during parsing. (The correct CVE ID year is 2020 [CVE-2020-25817, not CVE-2021-25817]).

Timeline

dates in UTC

2021-06-0818:15CVE 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-2020-25817?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-25817?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Silverstripe

Branch	Affected	Fixed in	Source
4.6	< 4.6.0	4.6.0	NVD · OSV
4.6	= 4.6.0	no fix published	NVD
4.6	≥ 4.6.0-rc1, ≤ 4.6.0-rc1	no fix published	OSV

silverstripe/framework

Branch	Affected	Fixed in	Source
4.x	≥ 4.0.0, < 4.7.4	4.7.4	OSV

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

Fix

Update Silverstripe to 4.6.0

Advisories and patches

forum.silverstripe.orgRelease Notes · Vendor Advisory
www.silverstripe.orgRelease Notes · Vendor Advisory
www.silverstripe.orgVendor Advisory

Detection

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

Sources

NVDCVSS 3.14.8read 2026-10-23
NVDCVSS 2.03.5read 2026-10-23
NVDweakness (CWE)CWE-611read 2026-10-23
FIRST EPSSEPSS score0.8 %2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
Published: 2021-06-08
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2020-25817?

Is CVE-2020-25817 actively exploited?

Active exploitation of CVE-2020-25817 has not been confirmed. Its EPSS score was 0.8% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-25817?

CVE-2020-25817 has a CVSS v3 base score of 4.8 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N.

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