SSRF via unnormalized IPv6-mapped loopback addresses
Published Sep 22, 2025 · Updated Sep 22, 2025
SSRF in is-localhost-ip 2.0.0 allows remote attackers to reach loopback services through IPv6-mapped IPv4 addresses. The isLocalhost function compares text against incomplete address patterns and returns false for the valid loopback form ::ffff:7f00:1 when canBind is false. Exploitation requires a consuming application to trust a false result before fetching attacker-controlled URLs, exposing otherwise unreachable local services or data.
Summary
What happened
SSRF in is-localhost-ip 2.0.0 allows remote attackers to reach loopback services through IPv6-mapped IPv4 addresses. The isLocalhost function compares text against incomplete address patterns and returns false for the valid loopback form ::ffff:7f00:1 when canBind is false. Exploitation requires a consuming application to trust a false result before fetching attacker-controlled URLs, exposing otherwise unreachable local services or data.
The record
- CVE
- CVE-2025-9960
- Published
- Sep 22, 2025
- Updated
- Sep 22, 2025
- Vendor
- Konstantin Vyatkin
- Product
- is-localhost-ip
- Classifications
- CWE-918, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 22, 2025CVE publishedPublication date reported by the CVE source.
- Sep 22, 2025Record 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=2.0.0
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
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Exploit-DB 52496 is-localhost-ip SSRF PoCproof of concept · demonstrated
- Fluid Attacks IPv6-mapped loopback bypass PoCproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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