CVE-2026-18646Public exploitNetwork attack vector

File-existence disclosure via traversable author names

Published Aug 3, 2026 · Updated Aug 3, 2026

Path traversal in HTMLy 3.1.1 and earlier allows remote attackers to probe server file existence through crafted author names. The public /author/:name handler concatenates the URL-supplied name into user-profile and theme-layout paths, then calls file_exists without rejecting traversal sequences. Authentication is not required; enforced suffixes prevent direct file reads, but response differences disclose whether targeted files or user records exist.

CVSS severity5.3
Medium
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Path traversal in HTMLy 3.1.1 and earlier allows remote attackers to probe server file existence through crafted author names. The public /author/:name handler concatenates the URL-supplied name into user-profile and theme-layout paths, then calls file_exists without rejecting traversal sequences. Authentication is not required; enforced suffixes prevent direct file reads, but response differences disclose whether targeted files or user records exist.

The record

CVE
CVE-2026-18646
Published
Aug 3, 2026
Updated
Aug 3, 2026
Vendor
Danang Probo Sayekti
Product
HTMLy
Classifications
CWE-22, T1083
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.1.0
  2. Affected versionversion=3.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Danang Probo Sayekti · HTMLyversion=3.1.0; version=3.1.1

Published CVSS scores

5.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1083File and Directory Discovery

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo