CVE-2023-6245Network attack vector

Canister service interruption via infinite decoding loop

Published Dec 8, 2023 · Updated Dec 2, 2024

Denial of service in DFINITY Candid 0.9.0 through 0.9.9 allows remote attackers to exhaust canister execution via crafted input. The Rust decoder treats an empty-typed extra record field as a recoverable skip error, re-enters field decoding, and never advances. Exposure requires a Rust canister interface expecting an open record; each request runs until the instruction limit traps, and repeated requests degrade availability.

CVSS severity7.5
High
EPSS probability1.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in DFINITY Candid 0.9.0 through 0.9.9 allows remote attackers to exhaust canister execution via crafted input. The Rust decoder treats an empty-typed extra record field as a recoverable skip error, re-enters field decoding, and never advances. Exposure requires a Rust canister interface expecting an open record; each request runs until the instruction limit traps, and repeated requests degrade availability.

The record

CVE
CVE-2023-6245
Published
Dec 8, 2023
Updated
Dec 2, 2024
Vendor
DFINITY Foundation
Product
Candid
Classifications
CWE-20, CWE-168, CWE-1288, CWE-835, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 8, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 2, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.9.0 <0.9.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

DFINITY Foundation · Candidversion=0.9.0 <0.9.10

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-168Improper Handling of Inconsistent Special Elements
CWE-1288Improper Validation of Consistency within Input
CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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