# Security Improvement: Subdomain Reuse Mitigation

DevFeed: [Security Improvement: Subdomain Reuse Mitigation](<https://devfeed.tech/articles/security-improvement-subdomain-reuse-mitigation-26468.md>)

Original publisher: [Read original article](<https://www.heroku.com/blog/mitigating-subdomain-reuse/>)

Author: Andre Soto

Published: 2023-07-20T19:06:48Z

Content type: release

Language: en

Sources: [Heroku](<https://devfeed.tech/sources/heroku.md>)

Topics: [Heroku](<https://devfeed.tech/topics/heroku.md>), [Security](<https://devfeed.tech/topics/security.md>), [Vulnerabilities](<https://devfeed.tech/topics/vulnerabilities.md>)

Tags: [cloud-infrastructure](<https://devfeed.tech/tags/cloud-infrastructure.md>), [developer-tools](<https://devfeed.tech/tags/developer-tools.md>), [heroku](<https://devfeed.tech/tags/heroku.md>), [news](<https://devfeed.tech/tags/news.md>), [platform](<https://devfeed.tech/tags/platform.md>), [redirection](<https://devfeed.tech/tags/redirection.md>), [security](<https://devfeed.tech/tags/security.md>), [security-compliance](<https://devfeed.tech/tags/security-compliance.md>), [vulnerability](<https://devfeed.tech/tags/vulnerability.md>)

## AI overview

Heroku changed the built-in domain format for its apps on 14 June 2023 to mitigate subdomain reuse, also known as subdomain takeover. The new format appends a random identifier, preventing deleted application names from being reused to take over former subdomains and reducing associated cookie-harvesting, phishing, and OAuth-token leakage risks.

## Source excerpt

Summary Subdomain reuse, also known as subdomain takeover, is a security vulnerability that occurs when an attacker claims and takes control of a target domain. Typically, this happens when an application is deprecated and an attacker directs residual traffic to a host that they control. As of 14 June 2023, we changed the format of [...] The post Security Improvement: Subdomain Reuse Mitigation appeared first on Heroku.