What is CVE-2025-1211?

Versions of the package hackney before 1.21.0 are vulnerable to Server-side Request Forgery (SSRF) due to improper parsing of URLs by URI built-in module and hackey. Given the URL http://127.0.0.1?@127.2.2.2/, the URI function will parse and see the host as 127.0.0.1 (which is correct), and hackney will refer the host as 127.2.2.2/. This vulnerability can be exploited when users rely on the URL function for host checking.

How severe is CVE-2025-1211?

No CVSS score has been assigned to CVE-2025-1211 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2025-1211?

CVE-2025-1211 affects the following packages: hackney (Hex). Ecosystems affected: Hex.

How do I fix CVE-2025-1211?

Update hackney to 1.21.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-1211 is resolved across your whole dependency graph.

How do I detect CVE-2025-1211 in my Hex dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hackney, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2025-1211 if there is no patch (or I can't update yet)?

Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.

Is CVE-2025-1211 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-1211 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2025-1211?

CVE-2025-1211 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 45th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2025-1211?

CVE-2025-1211 is classified as Server-Side Request Forgery (SSRF) (CWE-918). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2025-1211 published, and has it been updated?

CVE-2025-1211 was published on February 11, 2025 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2025-1211: hackney SSRF — Fixed in 1.21.0

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-1211.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs45th percentile — riskier than 45% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

💧hackney

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Hex packages — download data is not available via public APIs for these ecosystems.

Description

Versions of the package hackney before 1.21.0 are vulnerable to Server-side Request Forgery (SSRF) due to improper parsing of URLs by URI built-in module and hackey. Given the URL http://[email protected]/, the URI function will parse and see the host as 127.0.0.1 (which is correct), and hackney will refer the host as 127.2.2.2/. This vulnerability can be exploited when users rely on the URL function for host checking.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💧Hex	`hackney`	all versions	1.21.0`mix deps.update hackney`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hackney, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update hackney to 1.21.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-1211 is resolved across your whole dependency graph.
Workarounds
Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.

Frequently Asked Questions

Versions of the package hackney before 1.21.0 are vulnerable to Server-side Request Forgery (SSRF) due to improper parsing of URLs by URI built-in module and hackey. Given the URL http://[email protected]/, the URI function will parse and see the host as 127.0.0.1 (which is correct), and hackney will refer the host as 127.2.2.2/. This vulnerability can be exploited when users rely on the URL function for host checking.

O3 Security · Impact-Aware SCA

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CVE-2025-1211 — hackney