SSRF via unmatched loopback aliases in no_proxy
Published Apr 24, 2026 · Updated Apr 24, 2026
SSRF in Axios before 0.31.1 and 1.0.0 through 1.15.0 allows remote attackers to route loopback requests through a proxy. The shouldBypassProxy() function compares no_proxy hostnames as literal strings, so localhost, 127.0.0.1, and ::1 are not treated as equivalent. Exploitation requires attacker influence over an Axios request URL, a Node.js application using an environment proxy and no_proxy, and a proxy able to relay the loopback request, exposing internal response data.
Summary
What happened
SSRF in Axios before 0.31.1 and 1.0.0 through 1.15.0 allows remote attackers to route loopback requests through a proxy. The shouldBypassProxy() function compares no_proxy hostnames as literal strings, so localhost, 127.0.0.1, and ::1 are not treated as equivalent. Exploitation requires attacker influence over an Axios request URL, a Node.js application using an environment proxy and no_proxy, and a proxy able to relay the loopback request, exposing internal response data.
The record
- CVE
- CVE-2026-42038
- Published
- Apr 24, 2026
- Updated
- Apr 24, 2026
- Vendor
- Axios
- Product
- Axios
- Classifications
- CWE-918
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 24, 2026CVE publishedPublication date reported by the CVE source.
- Apr 24, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.31.1
- Affected versionversion=>= 1.0.0, < 1.15.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
- Axios no_proxy loopback-alias proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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