Is CVE-2026-40035 in the CISA KEV catalog?

No. CVE-2026-40035 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-40035?

CVE-2026-40035 has a CVSS v3 base score of 9.1 (CRITICAL).

What is the EPSS score for CVE-2026-40035?

CVE-2026-40035 has an EPSS score of 0.56% (42th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-40035

CRITICAL

9.1

CVSS v3

NVD

Description

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.

CWE-489

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Exploit Intelligence

0.56%probability of exploitation in 30 days

42ndpercentile

Moderate risk: more likely to be exploited than 42% of all known CVEs.

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-17.