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CVE-2021-21135

29
FAUCET Score

CVE-2021-21135 is a medium-severity vulnerability affecting Google Chrome and Microsoft Edge (Chromium-based) versions prior to 88.0.4324.96. It stems from an inappropriate implementation in the Performance API, allowing a remote attacker to leak cross-origin data through a specially crafted HTML page. The vulnerability has a CVSS score of 6.5, indicating a high potential for confidentiality impact with low attack complexity, requiring user interaction. While there is no evidence of active exploitation, public exploit code, or KEV listing, it has garnered some community discussion and media coverage, suggesting awareness within the cybersecurity community.

Impacted Technologies

VendorProductVersion(s)CPE
< 88.0.4324.96CPE matchmatch criteria
cpe:2.3:a:google:chrome:*:*:*:*:*:*:*:*
< 88.0.705.50CPE matchmatch criteria
cpe:2.3:a:microsoft:edge_chromium:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
19.23%
Probability of exploitation in next 30 days
EPSS Percentile
97.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.1923 is in the 99th percentile among its peer group of 26,236 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

microsoftpatch availablevia msrc
Product: Microsoft Edge (Chromium-based)
googlevendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

microsoft2021-Jan/CVE-2021-21135

Chromium CVE-2021-21135: Inappropriate implementation in Performance API

Jan 12, 2021

References

chromereleases.googleblog.com / 2021/01/stable-channel-update-for-desktop_19.html
Release NotesVendor Advisory
crbug.com / 1157818
Permissions RequiredThird Party Advisory
msrc.microsoft.com / update-guide/en-US/vulnerability/CVE-2021-21135
Third Party Advisory