# CVE-2026-4648: Insufficient Encryption Level in CasfID Servicios Tecnológicos NFC Wristbands

> Weak MIFARE Classic encryption allows attackers to clone NFC wristbands, steal balances, and impersonate users in cashless payment systems.

- **Severity:** Medium 6.8 (`CVSS:4.0/AV:P/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 28 Jul 2026
- **Updated:** 28 Jul 2026
- **Also known as:** GHSA-4x9m-p82w-8mmp

## What is CVE-2026-4648?

CVE-2026-4648 is a medium-severity vulnerability in CasfID Servicios Tecnológicos NFC Wristbands, published on 28 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Use of an insecure cryptographic algorithm in the cashless payment system using NFC wristbands from CasfID Servicios Tecnológicos S.L.U. (version used at Resurrection Fest 2025), which employs cards based on MIFARE Classic technology (FM11RF08S). The cryptographic weakness of the authentication algorithm allows an attacker to retrieve access keys using techniques known as Backdoored Nested Attack, read the wristband’s entire contents, and clone its credentials onto a compatible rewritable card. Exploitation of this vulnerability could enable the impersonation of other attendees, the fraudulent use of the balance associated with their wristbands, and financial losses for both the affected users and the event organizers.

Weakness: CWE-326 (Inadequate Encryption Strength)

## Which versions are affected by CVE-2026-4648?


## How do I fix CVE-2026-4648?

No fix has been published for CVE-2026-4648 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-4648 being exploited?

There is no known exploitation of CVE-2026-4648 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4648 and fix it if it is affected.

What it is: CVE-2026-4648 is a medium-severity vulnerability in CasfID Servicios Tecnológicos NFC Wristbands, published on 28 Jul 2026. 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-2026-4648 in the wild and no public exploit code.

Affected product: CasfID Servicios Tecnológicos NFC Wristbands. 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-2026-4648/ (Markdown: https://insights.sbomify.com/CVE-2026-4648/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4648
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4648
- OSV: https://osv.dev/vulnerability/CVE-2026-4648

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-4648/
Summaries are generated and may contain mistakes; the official description above is the record.