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Remote DoS in httpx 1.7.0 – Out-of-Bounds Read via Malformed <title> Tag


From: Brian Carpenter via Fulldisclosure <fulldisclosure () seclists org>
Date: Tue, 24 Jun 2025 16:04:56 +0000

Hey list,

You can remotely crash httpx v1.7.0 (by ProjectDiscovery) by serving a malformed <title> tag on your website. The bug 
is a classic out-of-bounds read in trimTitleTags() due to a missing bounds check when slicing the title string. It 
panics with:

panic: runtime error: slice bounds out of range [9:6]

Affects anyone using httpx in their automated scanning pipeline. One malformed HTML response = scanner down. Unit 
testing or fuzzing this function would’ve caught it in 5 minutes. But it’s “just a bug.” 😂

💥 Trigger input:

<title</></title>0

📍 Vulnerable code:

func trimTitleTags(title string) string {
    titleBegin := strings.Index(title, ">")
    titleEnd := strings.Index(title, "</")
    if titleEnd < 0 || titleBegin < 0 {
        return title
    }
    return title[titleBegin+1 : titleEnd] // ← PANIC here
}

✅ Fix:
https://github.com/projectdiscovery/httpx/pull/2198

📂 PoC + context:
https://github.com/projectdiscovery/httpx/issues/2197

Crash scanners. Create blind spots. Chain with HTML injection. Happy hunting.

Stay glitchy,

—geeknik
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