CVE-2026-8859: IBM Langflow OSS 1.0.0 through 1.10.0 Langflow could allow an attacker to write arbitrary files to unintended locations due to improper input validation in the APIRequest component

criticalCVSS 9.9CVE-2026-8859

IBM Langflow OSS 1.0.0 through 1.10.0 Langflow could allow an attacker to write arbitrary files to unintended locations due to improper input validation in the APIRequest component. A path traversal vulnerability exists when the "Save to File" feature is enabled, where filenames extracted from HTTP response Content-Disposition headers are not sanitized before being joined to the temporary directory path. An attacker controlling an external HTTP server can supply crafted filename values containing path traversal sequences (e.g., ../), enabling arbitrary file writes to locations accessible by the Langflow process.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: critical — CVSS 9.9
Published: 2026-07-17
Last updated: 2026-07-23
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-8859

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-88590.37% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 30% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-8859	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

unknownNCSC-2026-0251 [1.00] [M/H] Vulnerabilities fixed in IBM Langflow OSSncsc-nl
high[NEW] [high] IBM Langflow Desktop OSS: Multiple vulnerabilitiescert-bund

Recent advisories for IBM Langflow OSS

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

medium[NEW] [medium] IBM Langflow Desktop OSS: Vulnerability allows information disclosurecert-bund · 2026-07-31
criticalCVE-2026-12946: IBM Langflow OSS 1.0.0 through 1.10.0 could allow a remote attacker to inject arbitrary code o…nvd · 2026-07-30
highCVE-2026-13444: IBM Langflow OSS 1.0.0 through 1.10.1 can allow an attacker to access another user's private v…nvd · 2026-07-30
criticalCVE-2026-13435: IBM Langflow OSS 1.0.0 through 1.10.1 contains an improper input validation vulnerability in t…nvd · 2026-07-30
highCVE-2026-12942: IBM Langflow OSS 1.0.0 through 1.10.1 could allow a remote attacker to traverse directories on…nvd · 2026-07-30
mediumCVE-2026-10700: IBM Langflow OSS 1.0.0 through 1.8.4 contains multiple broken access control vulnerabilities i…nvd · 2026-07-30