Azle calling `setTimer` causes infinite loop of timers
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-835.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| demergent-labs | azle | 0.27.0 to before 0.30.0 | 0.30.0 | Patch available | CNA |
| — | azle (npm) | 0.27.0 to before 0.30.0 | 0.30.0 | Patch available | GHSA-xc76-5pf9-mx8m |
- azle Vendordemergent-labs Affected 0.27.0 to before 0.30.0 Fixed in 0.30.0 Patch available CNA
- azle (npm) Vendor— Affected 0.27.0 to before 0.30.0 Fixed in 0.30.0 Patch available GHSA-xc76-5pf9-mx8m
Remediation
- Fix · CNA azle (demergent-labs) Fixed in 0.30.0
- Fix · GHSA-xc76-5pf9-mx8m azle (npm) Fixed in 0.30.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2025-29776
- 2026-10-03 Alias added: GHSA-xc76-5pf9-mx8m
References
Sources
- CVE-2025-29776 · CVE Program
- CVE-2025-29776 · NVD
- FIRST EPSS
- GHSA-xc76-5pf9-mx8m · GitHub Advisory Database · CC BY 4.0
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