Node.js uninitialized memory exposure in Buffer.alloc and Uint8Array via vm timeout race
CVE-2025-55131 is a high-severity Node.js vulnerability in buffer/TypedArray allocation logic. When the vm module is used with the timeout option, a timeout-driven race can interrupt allocations such that Buffer.alloc and other TypedArray instances, including Uint8Array, may be returned without being fully zero-initialized. Under specific timing conditions, this exposes leftover heap contents from prior operations to JavaScript code. The issue can result in disclosure of in-process data such as tokens, passwords, or other sensitive material, and may also cause data corruption. The provided content identifies affected release lines as Node.js 20.x, 22.x, 24.x, and 25.x, and notes fixes shipped in 20.20.0, 22.22.0, 24.13.0, and 25.3.0.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
vm module with the timeout option, especially in code paths influenced by untrusted input. Reduce attacker influence over timing and workload shaping where feasible, and isolate untrusted code execution into separate processes or containers so that any memory disclosure cannot expose high-value secrets from the main application process. Minimize sensitive material resident in-process during execution of untrusted workloads.Remediation
Patch, then assume compromise.
Exploits
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No public exploit code observed for this vulnerability.
Affected products & vendors
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
22 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Unknown
A high-severity Node.js vulnerability that could be exploited to cause data leakage or corruption (no further technical details provided in the content).
High-severity uninitialized memory exposure in Node.js Buffer.alloc/Uint8Array related to vm module timeout races, potentially leaking sensitive data.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.