# 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.

- **Severity:** High 8.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Sep 2026
- **Updated:** 1 Oct 2026
- **Also known as:** CLEANSTART-2026-AQ06052, CLEANSTART-2026-MT76481, CLEANSTART-2026-OW20688, DEBIAN-CVE-2026-101909, ECHO-c7a0-be1c-dfd7, GHSA-x97p-jq2g-jp4f, MINI-59v7-6q9p-9w7x, MINI-6c8p-h274-3w2f, MINI-73cg-x4fr-7qvw, MINI-95wx-8726-x6gv, MINI-c26q-m275-2r8g, MINI-cmh5-w69f-7g9c, MINI-fr27-8967-93wq, MINI-fwph-jp2c-698j, MINI-h3m9-vj45-5f7x, MINI-w72g-g5v9-2598, MINI-x6hx-gxpv-hc7c, ROOT-APP-NPM-CVE-2026-101909, UBUNTU-CVE-2026-101909

## 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 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2026-101909?

4 open source packages ship an affected version, including axios.


| Package | Ecosystem | 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.

## Is CVE-2026-101909 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-101909 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-101909 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-101909 exists.

Affected packages and fixed versions:
- axios (npm): affected from 0.28.0; fixed in 0.34.0
- axios (npm): affected from 0.28.0; fixed in 0.34.0
- axios (npm): affected from 1.15.1; fixed in 1.20.0
- axios (npm): affected from 1.15.1; fixed in 1.20.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-101909/ (Markdown: https://insights.sbomify.com/CVE-2026-101909/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-101909
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-101909
- OSV: https://osv.dev/vulnerability/CVE-2026-101909

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-101909/
Summaries are generated and may contain mistakes; the official description above is the record.