CVE-2024-12224: idna accepts Punycode labels that do not produce any non-ASCII when decoded

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-05-30 · updated 2026-06-17
Weakness: CWE-1289

Description

Improper Validation of Unsafe Equivalence in punycode by the idna crate from Servo rust-url allows an attacker to create a punycode hostname that one part of a system might treat as distinct while another part of that system would treat as equivalent to another hostname.

Affected products

servo Idna: before 1.0.0 — fixed in 1.0.0
Crates.Io Idna: from 0.0.0-0 before 1.0.0 — fixed in 1.0.0

How to fix

Upgrade to a fixed version: servo Idna 1.0.0; Crates.Io Idna 1.0.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1887898
https://rustsec.org/advisories/RUSTSEC-2024-0421.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1887898

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