CVE-2026-21440: AdonisJS Path Traversal in Multipart File Handling

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 1.0%, percentile 63: FIRST’s model estimates a 1.0% chance of exploitation activity in the next 30 days, higher than 63% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes @adonisjs/bodyparser (npm) < 10.1.2, fixed in 10.1.2; @adonisjs/bodyparser (npm) >= 11.0.0-next.0, < 11.0.0-next.6, fixed in 11.0.0-next.6. Check your lockfile, including transitive dependencies.

What it is

AdonisJS is a TypeScript-first web framework. A Path Traversal vulnerability in AdonisJS multipart file handling may allow a remote attacker to write arbitrary files to arbitrary locations on the server filesystem. This impacts @adonisjs/bodyparser through version 10.1.1 and 11.x prerelease versions prior to 11.0.0-next.6. This issue has been patched in @adonisjs/bodyparser versions 10.1.2 and 11.0.0-next.6.

From the GitHub advisory

Summary

Description A Path Traversal (CWE-22) vulnerability in AdonisJS multipart file handling may allow a remote attacker to write arbitrary files to arbitrary locations on the server filesystem. This impacts @adonisjs/bodyparser through version 10.1.1 and 11.x prerelease versions prior to 11.0.0-next.6. This issue has been patched in @adonisjs/bodyparser versions 10.1.2 and 11.0.0-next.6.

Details AdonisJS parses multipart/form-data via BodyParser and exposes uploads as MultipartFile. The issue is in the MultipartFile.move(location, options) default options. If options.name isn't provided, it defaults to the unsanitized client filename and builds the destination with path.join(location, name), allowing a traversal to escape the default or intended directory chosen by the developer. If options.overwrite isn't provided, it defaults to true, allowing file overwrites. The documentation previously demonstrated examples leading developers to this vulnerable code path. Impact

Exploitation requires a reachable upload endpoint. If a developer uses MultipartFile.move() without the second options argument or without explicitly sanitizing the filename, an attacker can supply a crafted filename value containing traversal sequences, writing to a destination path outside the intended upload directory. This can lead to arbitrary file write on the server.

If the attacker can overwrite application code, startup scripts, or configuration files that are later executed/loaded, RCE is possible. RCE is not guaranteed and depends on filesystem permissions, deployment layout, and application/runtime behavior.

Weakness type: CWE-22.

Product: @adonisjs/bodyparser (npm) · Assigned by: GitHub_M · Published: 2026-01-02

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: present (depends on deployment conditions)
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 1.03% probability of exploitation activity in the next 30 days; percentile 63.

Timeline

• 2026-01-02 — CVE record published by GitHub_M
• 2026-01-02 — GitHub-reviewed advisory GHSA-gvq6-hvvp-h34h published (critical)
• 2026-01-05 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-gvq6-hvvp-h34h github.com
2. CVE.org record CVE-2026-21440 cve.org
3. NVD entry CVE-2026-21440 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com
5. github.com github.com

Critical npm advisories · Today’s Security Digest