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CVE-2022-28345

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2022-04-15 · updated 2026-06-17
• Weakness: CWE-74

Description

The Signal app before 5.34 for iOS allows URI spoofing via RTLO injection. It incorrectly renders RTLO encoded URLs beginning with a non-breaking space, when there is a hash character in the URL. This technique allows a remote unauthenticated attacker to send legitimate looking links, appearing to be any website URL, by abusing the non-http/non-https automatic rendering of URLs. An attacker can spoof, for example, example.com, and masquerade any URL with a malicious destination. An attacker requires a subdomain such as gepj, txt, fdp, or xcod, which would appear backwards as jpeg, txt, pdf, and docx respectively.

Affected products

• Signal: before 5.34 — fixed in 5.34

How to fix

Upgrade to a fixed version: Signal 5.34. Check the vendor advisory for mitigations.

References

• https://blog.malwarebytes.com/social-engineering/2022/03/uri-spoofing-flaw-could-phish-whatsapp-signal-instagram-and-imessage-users/
• https://github.com/sickcodes/security/blob/master/advisories/SICK-2022-42.md
• https://github.com/zadewg/RIUS
• https://sick.codes/sick-2022-42
• https://blog.malwarebytes.com/social-engineering/2022/03/uri-spoofing-flaw-could-phish-whatsapp-signal-instagram-and-imessage-users/
• https://github.com/sickcodes/security/blob/master/advisories/SICK-2022-42.md
• https://github.com/zadewg/RIUS
• https://sick.codes/sick-2022-42

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