Security readout for executives and security teams
Plain-English summary
Langflow before 1.9.1 allowed a logged-in user to access and execute another user's flow through the responses API. This can expose sensitive workflow data and alter or run AI workflows outside the user's authorization. CISA KEV listing indicates active exploitation has been observed.
Executive priority
Treat this as urgent for any internet-reachable or multi-user Langflow deployment. The issue is high severity, affects confidentiality and integrity, and is listed in CISA KEV. Patch to 1.9.1 promptly and review for possible unauthorized workflow access.
Technical view
CVE-2026-55255 is a CWE-639 IDOR in Langflow's /api/v1/responses endpoint. An authenticated attacker with low privileges can reference another user's flow ID, causing unauthorized flow execution. CVSS 8.4 reflects network access, high complexity, low privileges, no user interaction, changed scope, and high confidentiality and integrity impact.
Likely exposure
Organizations running langflow-ai/langflow versions earlier than 1.9.1 are affected, especially multi-user deployments where authenticated users can reach /api/v1/responses. Exposure depends on deployment access controls and whether untrusted or lower-privileged users have accounts.
Exploitation context
The source bundle marks this CVE as CISA KEV, so active exploitation is supported. Public sources describe the issue class and affected endpoint, but the bundle does not provide safe evidence of exploit volume, targeting patterns, or detailed exploitation conditions beyond authenticated access.
Researcher notes
The advisory identifies an IDOR tied to flow ownership checks in /api/v1/responses. The fix is referenced through PR 12832 and commit 2c9f498d664a3c32698b57d7c5e752625291060e. Evidence is sufficient for affected-version triage, but not for detailed attacker tradecraft.
Mitigation direction
- Upgrade Langflow to version 1.9.1 or later.
- Restrict access to Langflow while patching, especially for untrusted users.
- Review vendor advisory and release notes for any additional required actions.
- Monitor responses API activity for suspicious cross-user flow access.
- Rotate exposed secrets if unauthorized flow execution may have revealed them.
Validation and detection
- Inventory all Langflow deployments and record exact versions.
- Confirm no production instance is running a version earlier than 1.9.1.
- Review access logs for unusual /api/v1/responses activity.
- Check whether lower-privileged users can reach sensitive Langflow environments.
- Validate authorization behavior in a controlled test environment after upgrade.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-639: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-55255 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.4 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L1.86GitHub_MVulnerability scoring details
Base CVSS 3.1 score
8.4HighVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2CVE reference, GitHub_M · x_refsource_CONFIRM
- https://github.com/langflow-ai/langflow/pull/12832CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/langflow-ai/langflow/commit/2c9f498d664a3c32698b57d7c5e752625291060eCVE reference, GitHub_M · x_refsource_MISC
- https://webflow.sysdig.com/blog/understanding-langflow-cve-2026-55255-and-why-higher-cvss-vulnerabilities-arent-always-the-most-exploitedCVE reference, CISA-ADP · third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-55255CVE reference, CISA-ADP · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Authorization Bypass Through User-Controlled Key
Authorization Bypass Through User-Controlled Key represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.