How severe is CVE-2026-45728?

CVE-2026-45728 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-45728 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-45728?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-45728 have an EU (EUVD) identifier?

Yes. CVE-2026-45728 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31868.

When was CVE-2026-45728 published?

CVE-2026-45728 was published on 2026-05-26 and last updated on 2026-06-17.

CVE-2026-45728

CVE-2026-45728 is a high-severity vulnerability with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-209.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (22nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-31868
Weakness: CWE-209
Published: 2026-05-26
Last modified: 2026-06-17

Description

Algernon is a small self-contained pure-Go web server. Prior to 1.17.7, when Algernon is invoked with a single file path instead of a directory, singleFileMode is set to true and debugMode is forcibly enabled. debugMode activates the PrettyError renderer, which on any Lua or template error response dumps the absolute path of the file that errored, complete byte contents of that file, and exception or parser error text. This response is served with HTTP 200 OK to whoever sent the request that triggered the error. Any client able to reach the server and able to provoke a runtime error in the served script obtains the full server-side source of that script and of any sibling Lua data file consulted during the request. This vulnerability is fixed in 1.17.7.

Frequently asked questions

What is CVE-2026-45728?: Algernon is a small self-contained pure-Go web server. Prior to 1.17.7, when Algernon is invoked with a single file path instead of a directory, singleFileMode is set to true and debugMode is forcibly enabled. debugMode activates the PrettyError renderer, which on any Lua or template error response dumps the absolute path of the file that errored, complete byte contents of that file, and exception or parser error text. This response is served with HTTP 200 OK to whoever sent the request that triggered the error. Any client able to reach the server and able to provoke a runtime error in the served script obtains the full server-side source of that script and of any sibling Lua data file consulted during the request. This vulnerability is fixed in 1.17.7.
How severe is CVE-2026-45728?: CVE-2026-45728 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-45728 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-45728?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-45728 have an EU (EUVD) identifier?: Yes. CVE-2026-45728 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31868.
When was CVE-2026-45728 published?: CVE-2026-45728 was published on 2026-05-26 and last updated on 2026-06-17.

References

https://github.com/xyproto/algernon/security/advisories/GHSA-fwqx-8365-9983

Other CWE-209 (Generation of Error Message Containing Sensitive Information) vulnerabilities

CVE-2025-62168 — Critical (CVSS 10.0): Squid is a caching proxy for the Web. In Squid versions prior to 7.2, a failure to redact HTTP authentication…
CVE-2025-68110 — Critical (CVSS 9.9): ChurchCRM is an open-source church management system. Versions prior to 6.5.3 may disclose database information in an…
CVE-2025-46658 — Critical (CVSS 9.8): An issue was discovered in ExonautWeb in 4C Strategies Exonaut 21.6. There are verbose error messages.
CVE-2024-28285 — Critical (CVSS 9.8): A Fault Injection vulnerability in the SymmetricDecrypt function in cryptopp/elgamal.h of Cryptopp Crypto++ 8.9, allows…
CVE-2023-40767 — Critical (CVSS 9.8): User enumeration is found in in PHPJabbers Make an Offer Widget v1.0. This issue occurs during password recovery, where…
CVE-2023-40766 — Critical (CVSS 9.8): User enumeration is found in in PHPJabbers Ticket Support Script v3.2. This issue occurs during password recovery,…

Browse all CWE-209 (Generation of Error Message Containing Sensitive Information) vulnerabilities →