# CVE-2025-66038: OpenSC: `sc_compacttlv_find_tag` can return out-of-bounds pointers

> Attackers can trigger out-of-bounds pointer returns in OpenSC via crafted smart card data, potentially leading to memory corruption and code execution.

- **Severity:** Low 3.9 (`CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 30 Mar 2026
- **Updated:** 1 Apr 2026
- **Also known as:** AZL-81192, BELL-CVE-2025-66038, DEBIAN-CVE-2025-66038, GHSA-72x5-fwjx-2459, UBUNTU-CVE-2025-66038

## What is CVE-2025-66038?

CVE-2025-66038 is a low-severity memory corruption vulnerability in Opensc Project Opensc, published on 30 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

OpenSC is an open source smart card tools and middleware. Prior to version 0.27.0, sc_compacttlv_find_tag searches a compact-TLV buffer for a given tag. In compact-TLV, a single byte encodes the tag (high nibble) and value length (low nibble). With a 1-byte buffer {0x0A}, the encoded element claims tag=0 and length=10 but no value bytes follow. Calling sc_compacttlv_find_tag with search tag 0x00 returns a pointer equal to buf+1 and outlen=10 without verifying that the claimed value length fits within the remaining buffer. In cases where the sc_compacttlv_find_tag is provided untrusted data (such as being read from cards/files), attackers may be able to influence it to return out-of-bounds pointers leading to downstream memory corruption when subsequent code tries to dereference the pointer. This issue has been patched in version 0.27.0.

Weakness: CWE-126 (Buffer Over-read)

## Which versions are affected by CVE-2025-66038?

It affects 1 product.


Products: Opensc Project Opensc.

## How do I fix CVE-2025-66038?

Upgrade to a fixed version.

## Is CVE-2025-66038 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-66038 exists.

## Other vulnerabilities in Opensc Project Opensc

- [CVE-2021-34193](https://insights.sbomify.com/CVE-2021-34193/): Memory corruption in n/a (high 7.5)
- [CVE-2019-16058](https://insights.sbomify.com/CVE-2019-16058/): Memory corruption in n/a (high 7.5)
- [CVE-2019-6502](https://insights.sbomify.com/CVE-2019-6502/): Denial of service in n/a (high 7.5)
- [CVE-2023-2977](https://insights.sbomify.com/CVE-2023-2977/): Memory corruption in OpenSC (high 7.1)
- [CVE-2019-20792](https://insights.sbomify.com/CVE-2019-20792/): Use after free in n/a (medium 6.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-66038 and fix it if it is affected.

What it is: CVE-2025-66038 is a low-severity memory corruption vulnerability in Opensc Project Opensc, published on 30 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-66038 exists.

Affected product: Opensc Project Opensc. 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-2025-66038/ (Markdown: https://insights.sbomify.com/CVE-2025-66038/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-66038
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-66038
- OSV: https://osv.dev/vulnerability/CVE-2025-66038

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From sbomify Insights: https://insights.sbomify.com/CVE-2025-66038/
Summaries are generated and may contain mistakes; the official description above is the record.