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PatchSiren cyber security CVE debrief

CVE-2025-13826 Zervit CVE debrief

A remote denial-of-service vulnerability exists in Zervit's portable HTTP/web server. The flaw stems from insufficient validation of user-supplied input during configuration reset requests. An unauthenticated attacker can exploit this by sending malicious requests to trigger a DoS condition, requiring manual application restart to restore service. The vulnerability was published on 2026-04-21 and last modified on 2026-05-19. No known exploitation in ransomware campaigns has been documented, and the vulnerability is not listed in CISA's Known Exploited Vulnerabilities catalog.

Vendor
Zervit
Product
portable HTTP/Web server
CVSS
HIGH 8.2
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-21
Original CVE updated
2026-09-30
Advisory published
2026-04-21
Advisory updated
2026-09-30

Who should care

Organizations running Zervit portable HTTP/web server in production environments, particularly those with exposed management or configuration interfaces. Security teams responsible for availability of web services and infrastructure operators relying on Zervit for lightweight HTTP serving should prioritize assessment and remediation.

Technical summary

The vulnerability exists in the configuration reset functionality of Zervit's portable HTTP/web server. Insufficient validation of user-supplied input allows remote, unauthenticated attackers to send crafted requests that cause the application to stop responding. Successful exploitation results in a denial-of-service condition that can only be resolved through manual application restart. The attack requires network access to the server but no authentication or user interaction.

Defensive priority

high

Recommended defensive actions

  • Apply input validation to configuration reset endpoints
  • Implement rate limiting on administrative functions
  • Monitor for anomalous request patterns to configuration interfaces
  • Review and restrict network exposure of Zervit management interfaces
  • Establish automated health checks and restart procedures for service availability

Evidence notes

The vulnerability description indicates inadequate input validation (CWE-20) as the root cause. The CVSS 4.0 vector confirms network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), and high availability impact (VA:H). The vendor attribution is marked as low confidence based on reference domain analysis pointing to INCIBE.

Sources and references

Verified primary and authoritative sources

  • CVE-2025-13826 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2025-13826

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2025-13826 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2025-13826

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://www.incibe.es/en/incibe-cert/notices/aviso/incorrect-input-validation-zervit-portable-httpweb-server

    [email protected]

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.