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CVE-2021-20835

24
FAUCET Score

CVE-2021-20835 describes an improper authorization vulnerability in the Android app 'Mercari (Merpay) - Marketplace and Mobile Payments App' (Japan version) prior to 4.49.1. This flaw allows a remote attacker to redirect users to arbitrary websites and launch arbitrary in-app activities, potentially leading to the theft of Mercari account access tokens. Rated 7.5 HIGH on CVSS, the attack is network-based and low complexity, with a high impact on confidentiality. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage for this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.49.1CPE matchmatch criteria
cpe:2.3:a:mercari:mercari:*:*:*:*:*:android:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.33%
Probability of exploitation in next 30 days
EPSS Percentile
68.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0133 is in the 48th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

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

Remediation

Remediation records are not available for this CVE.

References

jvn.jp / en/jp/JVN49465877/index.html
Third Party Advisory