CVE-2026-40036
CVE-2026-40036 is a high-severity vulnerability in Ryandfir Unfurl with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-409.
Key facts
- Severity: High (CVSS 3.x base score 7.5)
- CVSS v4: 8.7
- EPSS exploit prediction: 1% (40th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-20779
- Weakness: CWE-409
- Affected product: Ryandfir Unfurl
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-40036?
- 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.
- How severe is CVE-2026-40036?
- CVE-2026-40036 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2026-40036 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-40036?
- CVE-2026-40036 affects Ryandfir Unfurl. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-40036?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-40036 have an EU (EUVD) identifier?
- Yes. CVE-2026-40036 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-20779.
- When was CVE-2026-40036 published?
- CVE-2026-40036 was published on 2026-04-08 and last updated on 2026-06-17.
References
- https://github.com/obsidianforensics/unfurl/releases/tag/v2026.04
- https://github.com/obsidianforensics/unfurl/security/advisories/GHSA-h5qv-qjv4-pc5m
- https://www.vulncheck.com/advisories/dfir-unfurl-denial-of-service-via-unbounded-zlib-decompression
Affected products (1)
- cpe:2.3:a:ryandfir:unfurl:*:*:*:*:*:*:*:*
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