20 Cache Poisoning Case Study | Depth Analysis of Real-world Bug Reports
A deep‑dive into real‑world cache‑poisoning flaws from bug bounty programs, this analysis dissects 20+ cases where attackers turned trusted HTTP headers into weapons. It explains how improper header handling (e.g., X‑Forwarded‑Host, Host, Vary) lets an attacker inject a malicious response into a shared cache, which is then served to other users. The write‑up walks through the discovery process – from identifying cacheable endpoints to crafting poisoned requests, confirming with a second fetch – and shows how the same pattern yielded XSS, open redirects, session fixation and even full account takeover. Each case study highlights the exact payload, why the cache trusted the attacker’s input, and the lessons that can be reused in future hunts. The article stresses mitigation: enforce strict input validation, use cache keys that incorporate all variable headers, set correct Vary directives, and treat any header originating from the client as untrusted. By extracting repeatable techniques, it has already netted researchers over $100,000 in bounties, and serves as a high‑value reference for any bug bounty hunter. #infosec #BugBounty #Cybersecurity #CachePoisoning #WebSecurity
https://medium.com/@Aacle/20-cache-poisoning-case-study-depth-analysis-of-real-world-bug-reports-d6aa02a6a44f?source=rss------bug_bounty-5
20 Cache Poisoning Case Study | Depth Analysis of Real-world Bug Reports

An in-depth analysis of real-world cache poisoning vulnerabilities discovered on major platforms, with extracted techniques and…

Medium
Advanced Web Cache Poisoning: Beyond the Basics
This article explores advanced web cache poisoning techniques that exploit modern, multi-layered caching architectures. The core vulnerability stems from inconsistencies in how different cache layers (Edge CDNs like Cloudflare/Fastly, application caches like Varnish/Nginx, and framework caches) normalize and handle cache keys and headers. Attackers can manipulate unkeyed headers and exploit normalization differences between layers to inject malicious responses into caches that will be served to subsequent users. Exploitation involves crafting requests with specially formatted headers that are normalized differently by various cache layers, ultimately poisoning the cache with malicious content. This can lead to widespread XSS attacks, session hijacking, DoS conditions, or serving arbitrary content to legitimate users. The attack surface has grown sophisticated due to complex CDN configurations and application-level caching, requiring deep understanding of each layer's cache key algorithm. Mitigation requires implementing consistent cache key construction across all layers, carefully auditing which headers are included/excluded from cache keys, normalizing headers consistently before caching, and implementing strict cache validation logic. Organizations must treat cache poisoning as a critical vulnerability given its potential for mass exploitation and the subtle nature of these attacks in complex modern web architectures. #infosec #BugBounty #CachePoisoning #CDN #WebSecurity #APISecurity
https://medium.com/@Aacle/advanced-web-cache-poisoning-beyond-the-basics-3df645bcbf95?source=rss------bug_bounty-5
Advanced Web Cache Poisoning: Beyond the Basics

A deep dive into modern cache poisoning techniques, real-world exploitation scenarios, and lessons from the trenches

Medium

#CachePoisoning #vulnerabilities found in 2 #DNS resolving apps

The makers of #BIND , the Internet’s most widely used software for resolving domain names, are warning of two vulnerabilities that allow attackers to poison entire caches of results and send users to #malicious destinations that are indistinguishable from the real ones.
#security

https://arstechnica.com/security/2025/10/bind-warns-of-bugs-that-could-bring-dns-cache-attack-back-from-the-dead/

Cache poisoning vulnerabilities found in 2 DNS resolving apps

At least one CVE could weaken defenses put in place following 2008 disclosure.

Ars Technica

Critical DNS cache poisoning in dnsmasq.

Sounds like the authors wanted to do coordinated disclosure but accidentally sent it to a public mailing list???

https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2025q3/018288.html

#dnsmasq #infosec #dns #cachepoisoning

[Dnsmasq-discuss] [Security Report] Critical Cache Poisoning Vulnerability in Dnsmasq

Cacheract: The Monster in your Build Cache

In this post, I demonstrate Cacheract, which is an open source proof-of-concept for “Cache Native Malware’ that exploits GitHub Actions cache misconfigurations.

Adnan Khan's Blog
The Monsters in Your Build Cache – GitHub Actions Cache Poisoning

GitHub Actions caching has some insecure design decisions that allow for some unique attacks. It’s considered working as intended, but there are many ways it can go wrong. Learn how I identif…

Adnan Khan

Well, it turns out we're not the only folks to find something in F5 this month:

https://my.f5.com/manage/s/article/K000137368

Sounds like someone else found a post-auth SQL Injection vuln. There's also some kind of cache poisoning issue that someone identified. More details on that at https://blog.malicious.group/from-akamai-to-f5-to-ntlm/#on-the-f5-hunt.

For the last issue the author was annoyed there was no bug bounty so they told F5 they were just gonna full disclosure. I suspect our bug was just bundled in with this release to get ahead of it.

Part of me would have loved the idea of accidentally stumbling onto a legit 0-day in the wild, but at this point I'm going to assume that's not the case until I see it proven otherwise.

#f5 #sqlinjection #cachepoisoning #vr #fulldisclosure

myF5

Sorry, but this is a dumb-ass idea. Short-term, it'll help a little and probably make caches less effective in the process. Some (really bad) caching software may break. Then the caches will switch to case-insensitive mode, and the software behind cache poisoning attacks will as well. Then it was all for nothing.

Security through obscurity isn't security.

#CachePoisoning #Google #DNSSecurity

https://www.theregister.com/2023/01/19/google_dns_queries/

If your DNS queries LoOk liKE tHIs, it's not a ransom note, it's a security improvement

It’s not Google's plan. There’s no way it’s Google's plan. It was Google's plan

The Register
How I Made $16,500 Hacking CDN Caching Servers — Part 1

This was actually my first Cache Poisoning, I initially reported it as a cache Deception issue, because that is all i knew about caching exploits at that time, and the reason how and why this ended…

InfoSec Write-ups
#HTTP header smuggling #attack against AWS API #Gateway exposes systems to #cachepoisoning . A #security researcher has explained how a #weakness in the #Amazon Web Services (AWS) API Gateway could be exploited via a #HTTP header smuggling #attack.
https://portswigger.net/daily-swig/http-header-smuggling-attack-against-aws-api-gateway-exposes-systems-to-cache-poisoning?&web_view=true
#fuckamazon
HTTP header smuggling attack against AWS API Gateway exposes systems to cache poisoning

New hacking technique may pave the way for other serious attacks