# CVE-2026-62647: Weak cryptography in Reyrolle 7SR5

> An attacker can predict session identifiers due to weak random number generation, allowing unauthorized access and impersonation of legitimate users on the device.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Sep 2026
- **Updated:** 14 Sep 2026
- **Also known as:** GHSA-677f-mg3g-pgv2

## What is CVE-2026-62647?

CVE-2026-62647 is a critical vulnerability in Siemens Reyrolle 7SR5, published on 8 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability has been identified in Reyrolle 7SR5 (All versions < V2.70). A random number generator is used to generate security-relevant values (such as session identifiers used for authentication purposes) that is not initialized with a True Random Number Generator (TRNG), resulting in a predictable sequence of generated values. This could allow an unauthenticated remote attacker to more easily predict the generated values and impersonate a legitimate authenticated user, potentially gaining unauthorized access to the device.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-62647?


## How do I fix CVE-2026-62647?

No fix has been published for CVE-2026-62647 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-62647 being exploited?

There is no known exploitation of CVE-2026-62647 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-62647 and fix it if it is affected.

What it is: CVE-2026-62647 is a critical vulnerability in Siemens Reyrolle 7SR5, published on 8 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-62647 in the wild and no public exploit code.

Affected product: Siemens Reyrolle 7SR5. 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-2026-62647/ (Markdown: https://insights.sbomify.com/CVE-2026-62647/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-62647
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-62647
- OSV: https://osv.dev/vulnerability/CVE-2026-62647

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-62647/
Summaries are generated and may contain mistakes; the official description above is the record.