CVE-2021-47348

What it actually does

The code reads 8 bytes instead of the intended 5 bytes from the HDCP target field using an oversized buffer, which can cause value corruption if the extra bytes are non-zero, resulting in potential information disclosure or data integrity issues.

Why it matters to the business

Organizations using affected systems may face risks of unauthorized data access or operational disruptions in display-related security features, requiring patching to the specified commit despite low exploit likelihood and high days since publication.

How an attack unfolds

An attacker sends crafted network requests that trigger the HDCP handling code, causing the oversized read and potential corruption or leak of adjacent memory values.

How to fix it

Apply the fix by updating hashicorp/vault (GIT) to commit 4c785b0584b9165a9d4410f22c7491a4c8eec95f which introduces an appropriately sized zero-initialized bounce buffer and limits the read to exactly 5 bytes.

How to confirm the fix worked

Confirm the corrected buffer allocation and read size are present in the source after the update and test HDCP field handling under conditions where trailing bytes would have been non-zero.

Typical attack path

1. Locate a reachable system running the vulnerable code path
2. Trigger HDCP target field access via network input
3. Force the over-read of 8 bytes instead of 5
4. Observe or manipulate the resulting corrupted u64 value

How to detect it

Inspect kernel or application logs for anomalies during HDCP field processing and review memory access patterns around the target buffer for signs of prior over-read attempts.

What your security team should do

• Upgrade all instances to the fixed commit without delay given the CVSS and network attack vector
• Review dependent packages for downstream impact from the original flaw
• Monitor EPSS and exploit maturity indicators for any future increase