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Vulnerability record · CVE-2026-40036 · published 8 April 2026

CVE-2026-40036: Ryandfir unfurl allocation without limits vulnerability

RRyandfir · Unfurl

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.

8.7 CVSS 4.0 High EPSS 0.79% · top 45.5% CWE-409 · CWE-409CWE-770 · Allocation without limits
8.7CVSS 4.0 base score
0.79%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References, 1 tagged exploit
24 Jul 2026Last modified by NVD

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.

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/obsidianforensics/unfurl/releases/tag/v2026.04 Release Notes
https://github.com/obsidianforensics/unfurl/security/advisories/GHSA-h5qv-qjv4-pc5m ExploitVendor Advisory
https://www.vulncheck.com/advisories/dfir-unfurl-denial-of-service-via-unbounded-zlib-decompression Third Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.3CVE-2026-40035Ryandfir unfurl vulnerabilityUnfurl through 2025.08 contains an improper input validation vulnerability in config parsing that enables Flask debug mode by default. The debug conf…EPSS 0.72%

Source: NIST National Vulnerability Database (record CVE-2026-40036), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.