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Vulnerabilities

Vulnerability · CVE-2026-40035

Unfurl through 2025.08 contains an improper input validation vulnerability in config parsing that enables Flask debug mode by default.

Published Apr 8, 2026 · catalog updated Oct 8, 2026 · Unfurl through 2025.08 contains

Check if you run it

No confirmed exploitation is on record for CVE-2026-40035. EPSS is 0.72%. Act only if a listed version of Unfurl through 2025.08 contains is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Unfurl through 2025.08 contains).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Critical9.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.72%
Remediation
Advisory link
Affected products
cpe ryandfir/unfurl

Unfurl through 2025.08 contains an improper input validation vulnerability in config parsing that enables Flask debug mode by default. The debug configuration value is read as a string and passed directly to app.run(), causing any non-empty string to evaluate truthy, allowing attackers to access the Werkzeug debugger and disclose sensitive information or achieve remote code execution.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe ryandfir/unfurlversion unspecified

How to fix CVE-2026-40035

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-40035. EPSS is 0.72%. Act only if a listed version of Unfurl through 2025.08 contains is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-489. EPSS 0.72%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 8, 2026 · NIST NVD

    Detected

    Unfurl through 2025.08 contains an improper input validation vulnerability in config parsing that enables Flask debug mode by default. The debug configuration value is read as a string and passed directly to app.run(), causing any non-empty string to evaluate truthy, allowing attackers to access the Werkzeug debugger and disclose sensitive information or achieve remote code execution.

  2. Oct 8, 2026 · NIST NVD

    Updated

    Unfurl through 2025.08 contains an improper input validation vulnerability in config parsing that enables Flask debug mode by default. The debug configuration value is read as a string and passed directly to app.run(), causing any non-empty string to evaluate truthy, allowing attackers to access the Werkzeug debugger and disclose sensitive information or achieve remote code execution.

Sources

  • CVE.orgVulnerability recordCVE-2026-40035

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-40035

    30-day exploitation probability 0.7%

    first.org
  • NIST NVDVulnerability recordCVE-2026-40035

    Unfurl through 2025.08 contains an improper input validation vulnerability in config parsing that enables Flask debug mode by default. The debug configuration value is read as a string and passed directly to app.run(), causing any non-empty string to evaluate truthy, allowing att

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.