In Azle, calling setTimer causes infinite loop of timers

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · 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 · score source

EPSS

• CVE-2025-29776: 0.38% estimated exploitation activity in the next 30 days; percentile 31.85 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact 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. Patches The problem has been fixed as of Azle version 0.30.0. Workarounds 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.

Published by the source

14 Mar 2025, 17:31 UTC

Last modified by the source

15 Mar 2025, 20:47 UTC

Source last checked

26 Oct 2026, 12:36 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-xc76-5pf9-mx8m

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-xc76-5pf9-mx8m

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# Patch Next advisory brief: CVE-2025-29776

Advisory: In Azle, calling `setTimer` causes infinite loop of timers
IDs: CVE-2025-29776, GHSA-xc76-5pf9-mx8m
Record: https://patchnext.com/advisories/cve-2025-29776 (revision 3, source checked 26 Oct 2026, 12:36 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: azle 0.30.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm azle: affected >= 0.27.0, < 0.30.0; fixed in 0.30.0

## Suggested inspection (read-only)
- `npm ls azle --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on azle.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-xc76-5pf9-mx8m (OSV record GHSA-xc76-5pf9-mx8m lists affected ranges: npm azle >=0.27.0 <0.30.0 (fixed))
- Verified: https://github.com/advisories/GHSA-xc76-5pf9-mx8m (GitHub-reviewed advisory GHSA-xc76-5pf9-mx8m lists affected ranges: npm azle >=0.27.0 <0.30.0)

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