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CVE-2020-21526

28
FAUCET Score

CVE-2020-21526 describes an arbitrary file writing vulnerability in Halo v1.1.3, specifically affecting its background file writing interface. This critical flaw, with a CVSS score of 9.8, allows unauthenticated attackers to bypass directory traversal checks using a manipulated 'startsWith' function, leading to full compromise of confidentiality, integrity, and availability. While no public exploits, Metasploit modules, or Nuclei templates are currently available, and there is minimal community discussion, the high severity warrants immediate attention.

Impacted Technologies

VendorProductVersion(s)CPE
1.1.3CPE matchmatch criteria
cpe:2.3:a:halo:halo:1.1.3:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.89%
Probability of exploitation in next 30 days
EPSS Percentile
77.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0189 is in the 66th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

github.com / halo-dev/halo/issues/421
ExploitIssue TrackingThird Party Advisory