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Security incidents tagged Vercel. Newest first.
› Next.js (next on npm), sharp / librsvg
On Oct 14 2026 Vercel shipped Next.js 16.4.1 and 15.5.28 with two critical unauthenticated remote code execution fixes held back from the September release: CVE-2026-96889 / GHSA-2464-fhr4-w9xw, a use-after-free in librsvg (via sharp) reachable through the Image Optimization API when SVGs are processed on glibc-based Linux, and GHSA-673q-mjm6-r5xr, RCE in App Router apps with Cache Components when a `use cache` function returns multiple typed arrays. A high-severity Server Actions DoS (GHSA-p3m5-59mp-jv5r) is fixed too. GitHub added the SVG advisory to its global database on Oct 22. No known exploitation.
› Linux kernel networking (host side of KVM/Firecracker and similar)
Paulos Yibelo / pwn.ai found a Critical Linux networking flaw (CVE-2026-99999, CVSS 9.3) during Vercel’s $1M Sandbox challenge. Guest-controlled checksum metadata can rewrite an IPv4 header after validation, enabling host-memory disclosure and, in lab conditions, guest-to-host code execution on KVM/Firecracker. Upstream fix merged Oct 2026; host kernels need patch + reboot. Affects multi-tenant VPS / sandbox providers more than end-user desktops.
› React Server Components (react-server-dom-*), Next.js
A flaw in how React Server Components deserialize Flight payloads let an unauthenticated request run code on the server. Next.js App Router apps were affected by default. China-nexus groups including Earth Lamia and Jackpot Panda exploited it within hours of disclosure. CVE-2025-66478 (the Next.js id) was rejected as a duplicate.
› Next.js (self-hosted) patched
Sending a crafted x-middleware-subrequest header made self-hosted Next.js skip middleware entirely, bypassing auth checks done there. Apps hosted on Vercel were protected. Fixed in 12.3.5, 13.5.9, 14.2.25 and 15.2.3; otherwise strip the header at the edge.
PwnEscape-Ai Research: Guest-to-Host KVM Escape (CVE-2026-99999). TLDR;- How a $1 million sandbox challenge led us to a vulnerability in Linux networking, repeatable host-memory disclosure, and ultimately a full guest-to-host escape. Blog:- t.co/CJERkG4rsE t.co/gdXbOvkklw
How can one obtain such a great identifier as CVE-2026-99999? #PwnEscape
Just uncovered: the “PwnEscape” Linux kernel flaw (CVE-2026-99999) lets guest VMs read host memory. A 9.3/10 critical issue, exposed via crafted packets in Vercel’s sandbox and patched in recent kernel versions. If you run shared Linux hosts, updating is mandatory. t.co/mqBjjVqe1d
‼️ ALERT - Next.js just shipped an out-of-band security update for TWO critical unauthenticated RCE flaws (both CVSS 9.5) + a high-severity DoS. RCEs: RSC use cache (GHSA-673q-mjm6-r5xr) and librsvg via sharp (CVE-2026-96889). 🔗 Read - t.co/ndnN46ysGv
🚨 CRITICAL: CVE-2026-96889 — Next.js Image Optimization RCE via SVG (librsvg/sharp) Score 9.5 (CVSS 4.0, Next.js advisory). Unauthenticated. Glibc Linux. Affects Next.js 10.0.0–15.5.27 and 16.0.0–16.4.0. Fixed in 15.5.28 and 16.4.1. Check npm ls sharp → 0.35.5+. Not in CISA
