CVE-2026-101909 Axios: Prototype Pollution Gadget in axios toFormData Options
Prototype pollution in Axios toFormData allows attackers to alter serialization, cause denial of service, or execute code if function injection is possible.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-101909?
CVE-2026-101909 is a high-severity unsafe deserialization vulnerability in axios, published on 28 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Axios is a promise-based HTTP client for the browser and Node.js. From 0.28.0 until 0.34.0 and 1.15.1 until 1.20.0, ToFormData processes inherited serialization options and visitor properties supplied through prototype pollution. A separate same-process prototype-pollution flaw supplies inherited dots, indexes, metaTokens, maxDepth, visitor, or Blob values before object serialization. The inherited options alter toFormData field naming and data interpretation, maxDepth can force request failure, Blob changes value handling, and a polluted visitor can execute when an attacker already has the stronger ability to inject a function. Serialized field naming and data interpretation can change, maxDepth can cause request failure, Blob can alter value handling, and a polluted visitor can execute under the stronger function-injection primitive. This issue is fixed in versions 0.34.0 and 1.20.0.
Weakness: CWE-1321
Which versions are affected by CVE-2026-101909?
4 open source packages ship an affected version, including axios.
| Package | Affected | Fixed in |
|---|---|---|
axios npm | From 0.28.0 | 0.34.0 |
axios npm | From 0.28.0 | 0.34.0 |
axios npm | From 1.15.1 | 1.20.0 |
axios npm | From 1.15.1 | 1.20.0 |
How do I fix CVE-2026-101909?
Upgrade axios to a fixed version for your release line: 0.34.0 or 1.20.0.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-101909 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-101909 exists.
Sources
Also known as CLEANSTART-2026-AQ06052, CLEANSTART-2026-MT76481, CLEANSTART-2026-OW20688, DEBIAN-CVE-2026-101909, ECHO-c7a0-be1c-dfd7, GHSA-x97p-jq2g-jp4f and 13 more.