# CVE-2026-63072: Heap Buffer Overflow in CMS Key Unwrapping

> An attacker can cause a denial of service by sending a crafted CMS message that triggers an 8-byte heap buffer overflow during decryption.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Aug 2026
- **Updated:** 25 Aug 2026
- **Also known as:** ALPINE-CVE-2026-63072, AZL-97665, AZL-97890, AZL-97947, BELL-CVE-2026-63072, CLEANSTART-2026-VK14120, CLSA-2026-1792183929, CLSA-2026-1792496065, DEBIAN-CVE-2026-63072, ECHO-aa38-89d5-f024, GHSA-wp5f-6q39-q2f4, MINI-mcq4-94wp-pxfr, MINI-r4gh-qcfr-6phw, OESA-2026-3922, OESA-2026-3924, RHSA-2026:85249, ROOT-OS-ALPINE-315-CVE-2026-63072, ROOT-OS-ALPINE-317-CVE-2026-63072, ROOT-OS-DEBIAN-11-CVE-2026-63072, SUSE-SU-2026:4034-1, SUSE-SU-2026:4036-1, SUSE-SU-2026:4037-1, SUSE-SU-2026:4042-1, UBUNTU-CVE-2026-63072

## What is CVE-2026-63072?

CVE-2026-63072 is a high-severity memory corruption vulnerability in Openssl Openssl, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Issue summary: OpenSSL CMS decryption sizes the key-unwrap output buffer based
on querying the unwrapped key size, but the AES-WRAP-PAD unwrap primitive
can write and cleanse more bytes than that query reports, causing an 8-byte
out-of-bounds heap write.

Impact summary: An attacker who supplies a crafted CMS message can trigger a
deterministic 8-byte out-of-bounds heap write when the victim decrypts it
with CMS_decrypt(), corrupting the heap and typically resulting in a Denial
of Service.

CWE: CWE-787: Out-of-bounds Write

Description: The key-wrap OID is potentially attacker-controlled on the wire.
CMS unwrapping allows both id-aesNNN-wrap-pad and id-aesNNN-wrap ciphers.
An attacker can take a legitimate message and change a single OID byte to
select the padded variant while leaving the message otherwise valid. Since
the unwrap key is derived from the recipient's private operation (ECDH key
agreement or ML-KEM decapsulation), the RFC 5649 integrity check cannot
pass, and the decryption fails with integrity failure.

The write is a fixed-size (8-byte), fixed-value (zero) heap overflow
immediately past the allocation, requires no special configuration, and is
reachable from the public CMS_decrypt() function. The consequence is
a heap corruption leading to a Denial of Service. The fix in the CMS code
sizes the unwrap output buffer for the worst case so a failed unwrap cannot
write past the allocation.

FIPS impact: no

As the CMS code lives outside the FIPS module boundary, no FIPS
modules are affected by this CVE.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-63072?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `openvox-agent` | Red Hat:rhel_satellite_openvox:6::el10 | All versions | 0:8.30.0-1.el10sat |
| `openvox-agent` | Red Hat:rhel_satellite_openvox:6::el7 | All versions | 0:8.30.0-1.el7sat |
| `openvox-agent` | Red Hat:rhel_satellite_openvox:6::el8 | All versions | 0:8.30.0-1.el8sat |
| `openvox-agent` | Red Hat:rhel_satellite_openvox:6::el9 | All versions | 0:8.30.0-1.el9sat |
| `openssl-1_1-livepatches` | SUSE:Linux Enterprise Live Patching 15 SP4 | All versions | 0.8-150400.3.26.1 |
| `openssl-1_1-livepatches` | SUSE:Linux Enterprise Live Patching 15 SP5 | All versions | 0.8-150500.6.17.1 |
| `openssl-1_1-livepatches` | SUSE:Linux Enterprise Live Patching 15 SP6 | All versions | 0.8-150600.11.9.1 |
| `openssl-1_1-livepatches` | SUSE:Linux Enterprise Live Patching 15 SP7 | All versions | 0.8-150700.13.12.1 |

Products: Openssl Openssl.

## How do I fix CVE-2026-63072?

Apply the vendor's patch.

## Is CVE-2026-63072 being exploited?

There is no known exploitation of CVE-2026-63072 in the wild and no public exploit code.

Public exploit code:

- CVE-2026-63072 (github_poc): https://github.com/0xredash/CVE-2026-63072

## Other vulnerabilities in Openssl Openssl

- [CVE-2009-3245](https://insights.sbomify.com/CVE-2009-3245/): Null dereference in n/a (critical 10.0)
- [CVE-2006-3738](https://insights.sbomify.com/CVE-2006-3738/): Memory corruption in n/a (critical 10.0)
- [CVE-2026-63073](https://insights.sbomify.com/CVE-2026-63073/): Untrusted Sender DN Used as Format String in CMP Response Validation (critical 9.8)
- [CVE-2016-6309](https://insights.sbomify.com/CVE-2016-6309/): Use after free in n/a (critical 9.8)
- [CVE-2016-0799](https://insights.sbomify.com/CVE-2016-0799/): Integer overflow in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63072 and fix it if it is affected.

What it is: CVE-2026-63072 is a high-severity memory corruption vulnerability in Openssl Openssl, published on 25 Aug 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-2026-63072 in the wild and no public exploit code.

Affected product: Openssl Openssl. 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-2026-63072/ (Markdown: https://insights.sbomify.com/CVE-2026-63072/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63072
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63072
- OSV: https://osv.dev/vulnerability/CVE-2026-63072

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63072/
Summaries are generated and may contain mistakes; the official description above is the record.