# CVE-2026-31251: FunAudioLLM CosyVoice insecure deserialization in gRPC server

Source: https://junglewise.ai/threats/cve-2026-31251-funaudiollm-cosyvoice-insecure-deserialization-in-grpc-server  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-11. Updated: 2026-05-14  
License: CC BY 4.0 with a link back

CVE-2026-31251 · Severity: high · CVSS 7.3 · Published 2026-05-11

CosyVoice, a large-scale voice generation and speech synthesis model, is vulnerable to a security flaw that allows for the execution of unauthorized commands. This occurs when the system loads a specially crafted AI model file from a directory specified by the user. If an attacker provides a malicious model file and a user attempts to start the voice server using that directory, the attacker can take full control of the victim's computer.

Technologies: [FunAudioLLM CosyVoice](https://junglewise.ai/threats/technologies/cosyvoice). Vendors: [FunAudioLLM](https://junglewise.ai/threats/vendors/funaudiollm).

## Quick answers

**Is CVE-2026-31251 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-31251 being exploited in the wild.

**How severe is CVE-2026-31251?** High severity, with a CVSS score of 7.3, published 11 May 2026.

**Which products and versions are affected?** FunAudioLLM CosyVoice thru commit 6e01309e01bc93bbeb83bdd996b1182a81aaf11e, up to commit 6e01309e01bc93bbeb83bdd996b1182a81aaf11e.

**Is there a fix for CVE-2026-31251?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-31251 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-31251?** Check whether you run FunAudioLLM CosyVoice at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An insecure deserialization vulnerability (CWE-502) exists in the gRPC server component of CosyVoice. The root cause is the use of the `torch.load()` function without the `weights_only=True` parameter when loading speech synthesis models from a user-specified directory. Because `torch.load()` utilizes the Python `pickle` module by default, it can be coerced into deserializing arbitrary Python objects. An attacker can exploit this by placing a malicious model file in a directory that the victim then points the gRPC server to during initialization. Successful exploitation results in arbitrary code execution with the privileges of the user running the server.

## Affected products

- FunAudioLLM CosyVoice thru commit 6e01309e01bc93bbeb83bdd996b1182a81aaf11e

## Timeline

- 2026-05-11: advisory: NVD publication date

## References

- [https://github.com/FunAudioLLM/CosyVoice](https://github.com/FunAudioLLM/CosyVoice)
- [https://www.notion.so/CVE-2026-31251-35d1e1393188816f9bf5f3ccea3aa16f](https://www.notion.so/CVE-2026-31251-35d1e1393188816f9bf5f3ccea3aa16f)

## Related threats

- [FunAudioLLM CosyVoice insecure deserialization in model loading](https://junglewise.ai/threats/cve-2026-31232-funaudiollm-cosyvoice-insecure-deserialization-in-model-loading)
- [FunAudioLLM CosyVoice insecure deserialization in model loading](https://junglewise.ai/threats/cve-2026-31252-funaudiollm-cosyvoice-insecure-deserialization-in-model-loading)
- [FunAudioLLM CosyVoice insecure deserialization in average_model.py](https://junglewise.ai/threats/cve-2026-31250-funaudiollm-cosyvoice-insecure-deserialization-in-average-model)
- [FunAudioLLM CosyVoice insecure deserialization in make_parquet_list.py](https://junglewise.ai/threats/cve-2026-31249-funaudiollm-cosyvoice-insecure-deserialization-in-make-parquet)