CVE-2026-33017
CVE-2026-33017 is a security flaw in Langflow, a tool for building AI apps. Attackers can run their own code on Langflow from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 25 Mar 2026.[1]
Langflow is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Langflow has published a fix or advice.
Description
CISA calls it a code injection in Langflow Langflow. In its words: “Langflow contains a code injection vulnerability that could allow building public flows without requiring authentication.”[1]
The CVE record adds: “Langflow is a tool for building and deploying AI-powered agents and workflows. In versions prior to 1.9.0, the POST /api/v1/build_public_tmp/{flow_id}/flow endpoint allows building public flows without requiring authentication. When the optional data parameter is supplied, the endpoint uses attacker-controlled flow data (containing arbitrary Python code in node definitions) instead of the stored flow data from the database. This code is passed to exec() with zero sandboxing, resulting in unauthenticated remote code execution. This is distinct from CVE-2025-3248, which fixed /api/v1/validate/code by adding authentication. The build_public_tmp endpoint is designed to be unauthenticated (for public flows) but incorrectly accepts attacker-supplied flow data containing arbitrary executable code. This issue has been fixed in version 1.9.0.”[2]
The underlying weakness is code injection (CWE-94), CWE-95, missing authentication (CWE-306), in MITRE’s list of common software weaknesses.
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Langflow’s advisory has them[3]. CISA names the product as Langflow Langflow.
Most families won’t have Langflow; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 25 Mar 2026, 5 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 8 Apr 2026 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 96%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
Langflow has published a fix or advice.[3] CISA’s 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.”[1]
- Check whether you use it.Langflow is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 8 Apr 2026 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 96%.[4] |
See also
Other Langflow flaws
- CVE-2026-0770: inclusion of functionality from untrusted control sphere ·
- CVE-2026-55255: authorization bypass through user-controlled key ·
- CVE-2025-34291: origin validation error ·
- CVE-2025-3248: missing authentication ·
Other code injection flaws
- CVE-2026-0322, Palo Alto Networks PAN-OS: code injection ·
- CVE-2026-65660, Microsoft SharePoint: code injection ·
- CVE-2026-60004, Gitea: code injection ·
- CVE-2026-72530, TrueConf Server: code injection ·
- CVE-2025-62593, Ray-Project Ray: code injection ·
Every Langflow flaw on CISA’s list · Everything added in March 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Langflow Code Injection Vulnerability”. Known Exploited Vulnerabilities Catalog, added 25 Mar 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-33017 Detail”. National Vulnerability Database, published 20 Mar 2026.
- ^ Langflow. Advisories and fixes: github.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.962, percentile 99.9, 31 Oct 2026.
- CVE Program. “CVE-2026-33017”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.