Cross-resource access via unchecked Digest URI
Published May 12, 2026 · Updated May 12, 2026
Authentication bypass in Espressif Systems Arduino-ESP32 before 3.3.8 allows remote attackers to read protected WebServer content via URI replay. WebServer.cpp builds HA2 from the client-supplied Digest uri value but never checks that value against the URI in the HTTP request line. A valid Digest response for any URI on the server, obtained from known credentials or observed traffic, is sufficient to read content returned by another protected endpoint.
Summary
What happened
Authentication bypass in Espressif Systems Arduino-ESP32 before 3.3.8 allows remote attackers to read protected WebServer content via URI replay. WebServer.cpp builds HA2 from the client-supplied Digest uri value but never checks that value against the URI in the HTTP request line. A valid Digest response for any URI on the server, obtained from known credentials or observed traffic, is sufficient to read content returned by another protected endpoint.
The record
- CVE
- CVE-2026-42855
- Published
- May 12, 2026
- Updated
- May 12, 2026
- Vendor
- Espressif Systems
- Product
- Arduino-ESP32
- Classifications
- CWE-287, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 12, 2026CVE publishedPublication date reported by the CVE source.
- May 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 3.3.8
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Public exploit references
- Upstream Digest URI mismatch proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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