CVE-2025-34291: Langflow Origin Validation Error Vulnerability

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Yes, if you run Langflow Langflow. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-05-21, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-06-04; treat that as the outer limit, not the target.
• EPSS 92.8%, percentile 99.8: FIRST’s model estimates a 92.8% chance of exploitation activity in the next 30 days, higher than 99.8% of all scored CVEs (very high). EPSS is a probability, not a verdict.
• Only applies if your dependency tree includes langflow (PyPI) <= 1.6.9, fixed in 1.7.0. Check your lockfile, including transitive dependencies.
• Editorial verdict: Act now. Langflow CVE-2026-9198: Exploited Unauthenticated RCE — Langflow is now the most repeatedly exploited AI-agent builder on CISA's list; any network-reachable instance below 1.10.1 should be patched today and checked for compromise.

What it is

Langflow versions up to and including 1.6.9 contain a chained vulnerability that enables account takeover and remote code execution. An overly permissive CORS configuration (alloworigins='' with allowcredentials=True) combined with a refresh token cookie configured as SameSite=None allows a malicious webpage to perform cross-origin requests that include credentials and successfully call the refresh endpoint. An attacker-controlled origin can therefore obtain fresh accesstoken / refreshtoken pairs for a victim session. Obtained tokens permit access to authenticated endpoints — including built-in code-execution functionality — allowing the attacker to execute arbitrary code and achieve full system compromise.

From the GitHub advisory

Langflow versions up to and including 1.6.9 contain a chained vulnerability that enables account takeover and remote code execution. An overly permissive CORS configuration (alloworigins='' with allowcredentials=True) combined with a refresh token cookie configured as SameSite=None allows a malicious webpage to perform cross-origin requests that include credentials and successfully call the refresh endpoint. An attacker-controlled origin can therefore obtain fresh accesstoken / refreshtoken pairs for a victim session. Obtained tokens permit access to authenticated endpoints — including built-in code-execution functionality — allowing the attacker to execute arbitrary code and achieve full system compromise.

CISA’s summary

Langflow contains an origin validation error vulnerability in which an overly permissive CORS configuration combined with a refresh token cookie configured as SameSite=None allows a malicious webpage to perform cross-origin requests that include credentials and successfully call the refresh endpoint. This could allow the attacker to execute arbitrary code and achieve full system compromise via obtained tokens that permit access to authenticated endpoints.

Weakness type: CWE-346.

Product: Langflow Langflow · Assigned by: VulnCheck · Published: 2025-12-05

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: passive

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: added 2026-05-21; federal due date 2026-06-04. Known ransomware use: Unknown.
• CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
• CISA SSVC assessment: exploitation active, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 92.81% probability of exploitation activity in the next 30 days; percentile 99.8.

Timeline

• 2025-12-05 — CVE record published by VulnCheck
• 2025-12-06 — GitHub-reviewed advisory GHSA-577h-p2hh-v4mv published (critical)
• 2026-05-21 — Added to CISA’s Known Exploited Vulnerabilities catalog
• 2026-06-04 — CISA remediation deadline for US federal agencies
• 2026-08-04 — erroneo.us brief: Langflow CVE-2026-9198: Exploited Unauthenticated RCE
• 2026-10-08 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. Listed in CISA KEV notes (github.com) github.com
2. Listed in CISA KEV notes (github.com) github.com
3. Listed in CISA KEV notes (github.com) github.com

Vulnerability records

1. GitHub Advisory GHSA-577h-p2hh-v4mv github.com
2. CVE.org record CVE-2025-34291 cve.org
3. NVD entry CVE-2025-34291 nvd.nist.gov

Government

1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov

Other references from the CVE record and advisory

1. obsidiansecurity.com obsidiansecurity.com
2. vulncheck.com vulncheck.com
3. crowdsec.net crowdsec.net
4. github.com github.com
5. github.com github.com
6. github.com github.com
7. github.com github.com
8. github.com github.com

All exploited Langflow vulnerabilities · Critical PyPI advisories · Today’s Security Digest