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Mallory
CriticalPublic exploit

Improper cipher finalization in Deno node:crypto allows infinite encryptions

IdentifiersCVE-2026-22863CWE-325· Missing Cryptographic Step

In Deno versions prior to 2.6.0, the Node.js compatibility crypto layer (node:crypto) fails to properly finalize cipher objects. Specifically, calling cipher.final() does not correctly conclude/close the cipher state; the cipher can remain active (e.g., a Cipheriv object remains usable with internal buffering state still accessible) rather than transitioning to a closed CipherBase state. This enables an attacker to perform repeated/infinite encryptions using the same cipher context, which can be leveraged for brute-force and more refined cryptanalytic attacks aimed at learning server secrets. The issue is fixed in Deno 2.6.0.

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ANALYST BRIEF

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.

Attackers can obtain an unlimited encryption oracle due to improper cipher finalization, enabling naive brute-force attempts and more advanced attacks intended to recover or infer server secrets. Reported scoring indicates high confidentiality impact (e.g., AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

Mitigation

If you can’t patch tonight, do this now.

Prevent exposure of vulnerable Deno runtimes by upgrading to Deno v2.6.0+; until upgraded, avoid relying on the affected node:crypto cipher finalization semantics in security-sensitive contexts where an attacker could obtain repeated encryption queries.

Remediation

Patch, then assume compromise.

Upgrade Deno to version 2.6.0 or later, where node:crypto cipher finalization behavior is corrected.
PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

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VendorProductType
DenoDenoapplication

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What this page doesn’t show

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Exposure mapping

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Threat actor evidence

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Associated malware

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Detection signatures

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Vendor-by-vendor mapping

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Social activity3

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