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Infinite LoopWeakness · CWE-835

CVE-2025-29776

HIGH · 8.7 CVSS v4.0 Published 2025-03-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
96/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Azle is a WebAssembly runtime for TypeScript and JavaScript on ICP. Calling `setTimer` in Azle versions `0.27.0`, `0.28.0`, and `0.29.0` causes an immediate infinite loop of timers to be executed on the canister, each timer attempting to clean up the global state of the previous timer. The infinite loop will occur with any valid invocation of `setTimer`. The problem has been fixed as of Azle version `0.30.0`. As a workaround, if a canister is caught in this infinite loop after calling `setTimer`, the canister can be upgraded and the timers will all be cleared, thus ending the loop.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In Azle versions 0.27.0 through 0.29.0, the setTimer function contains a logic flaw where each timer execution attempts to clean up the previous timer's global state, which triggers another timer execution. This creates an immediate infinite loop that consumes all canister resources, effectively causing a denial of service.

MitigationUpgrade Azle to version 0.30.0 or later. For canisters already stuck in the infinite loop, perform a canister upgrade to clear the timers and break the cycle.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Azle version
    Locate the Azle version specified in your project's dependency configuration (package.json, Cargo.toml, or dfx.json) and compare it to the affected range 0.27.0 through 0.29.0
    Affected if The installed Azle version falls within 0.27.0 to 0.29.0 inclusive
  2. Verify setTimer usage
    Search your canister source code for any calls to setTimer, setTimerInterval, or related timer functions provided by Azle
    Affected if The canister code invokes any Azle timer functions while using an affected version
  3. Observe canister resource consumption
    Monitor the canister's cycle balance and compute budget usage via dfx canister status or Internet Computer dashboard; look for rapid depletion or stuck execution
    Affected if The canister exhibits abnormally high or exhausted resources without expected workload, suggesting an infinite loop
  4. Check for stuck execution
    Execute a canister call or query operation and observe if the call times out or fails to respond, indicating the timer loop is consuming all available resources
    Affected if Canister operations hang or timeout due to resource exhaustion consistent with the timer loop behavior

A canister is affected if it runs Azle version 0.27.0-0.29.0, uses setTimer or timer functions, and is experiencing resource exhaustion or stuck execution.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Azle to version 0.30.0 or later. For canisters already stuck in the infinite loop, perform a canister upgrade to clear the timers and break the cycle.

Recommended fix High confidence

Azle version 0.30.0

  1. Upgrade Azle from version 0.27.0, 0.28.0, or 0.29.0 to version 0.30.0 in your project dependencies
  2. Update your package.json or dependency lock file to specify Azle version 0.30.0 or later
  3. Run dependency update to install the fixed version
  4. If the canister is already stuck in an infinite loop from a prior setTimer call, perform a canister upgrade which will clear all pending timers and terminate the loop
  5. After upgrading, test that setTimer functions correctly without triggering infinite loops
Caveat Review Azle 0.30.0 release notes for any breaking changes between 0.29.x and 0.30.0

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,900
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-29776 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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