# CVE-2025-12888: Constant Time Issue with Xtensa-based ESP32 and X22519

> Timing side channels in X25519 on Xtensa ESP32 allow attackers to potentially recover private keys via timing analysis.

- **Severity:** Low 1.0 (`CVSS:4.0/AV:P/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Nov 2025
- **Updated:** 8 Dec 2025
- **Also known as:** DEBIAN-CVE-2025-12888, GHSA-xmgq-3783-qgm4, UBUNTU-CVE-2025-12888

## What is CVE-2025-12888?

CVE-2025-12888 is a low-severity vulnerability in Wolfssl Wolfssl, published on 21 Nov 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Vulnerability in X25519 constant-time cryptographic implementations due to timing side channels introduced by compiler optimizations and CPU architecture limitations, specifically with the Xtensa-based ESP32 chips. If targeting Xtensa it is recommended to use the low memory implementations of X25519, which is now turned on as the default for Xtensa.

Weakness: CWE-203 (Observable Discrepancy)

## Which versions are affected by CVE-2025-12888?

It affects 1 product.


Products: Wolfssl Wolfssl.

## How do I fix CVE-2025-12888?

No fix has been published for CVE-2025-12888 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-12888 being exploited?

There is no known exploitation of CVE-2025-12888 in the wild and no public exploit code.

## Other vulnerabilities in Wolfssl Wolfssl

- [CVE-2024-5991](https://insights.sbomify.com/CVE-2024-5991/): Buffer overread in domain name matching (critical 10.0)
- [CVE-2021-37155](https://insights.sbomify.com/CVE-2021-37155/): Security feature bypass in n/a (critical 9.8)
- [CVE-2020-36177](https://insights.sbomify.com/CVE-2020-36177/): Memory corruption in n/a (critical 9.8)
- [CVE-2014-2896](https://insights.sbomify.com/CVE-2014-2896/): Memory corruption in n/a (critical 9.8)
- [CVE-2014-2897](https://insights.sbomify.com/CVE-2014-2897/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-12888 and fix it if it is affected.

What it is: CVE-2025-12888 is a low-severity vulnerability in Wolfssl Wolfssl, published on 21 Nov 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-12888 in the wild and no public exploit code.

Affected product: Wolfssl Wolfssl. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-12888/ (Markdown: https://insights.sbomify.com/CVE-2025-12888/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-12888
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-12888
- OSV: https://osv.dev/vulnerability/CVE-2025-12888

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-12888/
Summaries are generated and may contain mistakes; the official description above is the record.