CVE-2026-40036

Unfurl < 2026.04 - Denial of Service via Unbounded zlib Decompression

State: Published
Severity: 8.7 High
Published: Apr 8, 2026
Updated: Oct 8, 2026
Reserved: Apr 8, 2026

Description

Unfurl before 2026.04 contains an unbounded zlib decompression vulnerability in parse_compressed.py that allows remote attackers to cause denial of service. Attackers can submit highly compressed payloads via URL parameters to the /json/visjs endpoint that expand to gigabytes, exhausting server memory and crashing the service.

Scores

CVSS	Score	Vector	Source
4.0	8.7 High	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N	VulnCheck
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	VulnCheck

Weaknesses

CWE-770 Allocation of Resources Without Limits or Throttling
CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

Affected Products

Product	Versions
unfurlobsidianforensics	before 2026.04Affected

References

GHSA Advisory GHSA-h5qv-qjv4-pc5mvendor-advisory
VulnCheck Advisory: dfir-unfurl - Denial of Service via Unbounded zlib Decompressionrelease-notespatch
https://www.vulncheck.com/advisories/dfir-unfurl-denial-of-service-via-unbounded-zlib-decompressionthird-party-advisory

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