CVE-2025-3248
CVE-2025-3248 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 5 May 2025, and says ransomware gangs have used it.[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. Fixed in version 1.3.0 of langflow.
Description
CISA calls it a missing authentication in Langflow Langflow. In its words: “Langflow contains a missing authentication vulnerability in the /api/v1/validate/code endpoint that allows a remote, unauthenticated attacker to execute arbitrary code via crafted HTTP requests.”[1]
The underlying weakness is missing authentication (CWE-306), in MITRE’s list of common software weaknesses.[2]
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 lists one fixed version: everything before it is affected.[2]
| Product | Fixed in |
|---|---|
| langflow | 1.3.0 |
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 5 May 2025, 28 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 26 May 2025 to fix it.[1] CISA says ransomware gangs have used it.
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 over 99%. That’s in the top 1% of the flaws it scores.[3]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
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 (fixed in version 1.3.0 of langflow), or not in use. CISA gave US government agencies until 26 May 2025 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, noting that ransomware gangs have used it.[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 over 99%.[3] |
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-2026-33017: code injection ·
Other missing authentication flaws
- CVE-2026-111357, Ivanti Connect Secure: missing authentication for critical function ·
- CVE-2026-67277, MikroTik RouterOS: missing authentication for critical function ·
- CVE-2026-81578, PaperCut NG/MF: missing authentication for critical function ·
- CVE-2026-72529, TrueConf Server: missing authentication for critical function ·
- CVE-2026-56164, Microsoft SharePoint Server: missing authentication for critical function ·
Every Langflow flaw on CISA’s list · Everything added in May 2025
References
- ^ Cybersecurity and Infrastructure Security Agency. “Langflow Missing Authentication Vulnerability”. Known Exploited Vulnerabilities Catalog, added 5 May 2025.
- ^ National Institute of Standards and Technology. “CVE-2025-3248 Detail”. National Vulnerability Database, published 7 Apr 2025.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 1.000, percentile 100.0, 31 Oct 2026.
- CVE Program. “CVE-2025-3248”. 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.