CVE-2024-7531

What it actually does

Calling PK11_Encrypt with CKM_CHACHA20 using the same buffer for input and output produces plaintext output on Intel Sandy Bridge processors, exposing data that should remain encrypted during QUIC header protection when ChaCha20-Poly1305 is in use.

Why it matters to the business

Organizations running affected packages on AlmaLinux 8 face potential exposure of encrypted traffic metadata, leading to possible connection failures or limited traffic correlation by observers; low exploit likelihood means limited operational disruption but still requires timely patching of the listed modules to maintain cryptographic integrity.

How an attack unfolds

An attacker positioned as a network observer triggers repeated use of the affected ChaCha20 encryption path during QUIC connections; on Sandy Bridge hardware the overlapping buffer produces observable plaintext, allowing identification of packets from the same source across network path changes if the connection survives high packet loss.

How to fix it

Update custodia to 0.6.0-3.module_el8.6.0+2881+2f24dc92, python3-custodia to the same, python3-jwcrypto to 0.5.0-1.module_el8.5.0+2603+92118e57, python3-pyusb to 1.0.0-9.module_el8.5.0+2603+92118e57, python3-qrcode to 5.1-12.module_el8.5.0+2603+92118e57, python3-qrcode-core to 5.1-12.module_el8.6.0+2737+7e73ea90, and python3-yubico to 1.3.2-9.module_el8.6.0+2737+7e73ea90 on AlmaLinux 8 systems.

How to confirm the fix worked

Confirm package versions match the fixed releases above via package manager queries; test QUIC connections using ChaCha20-Poly1305 on Sandy Bridge hardware to verify absence of plaintext leakage and successful header protection.

Typical attack path

1. Identify targets using ChaCha20-Poly1305 over QUIC with affected NSS versions
2. Observe network traffic and induce or wait for overlapping-buffer encryption calls
3. Capture resulting plaintext artifacts to correlate sessions across path migrations

How to detect it

Review system logs and package inventories for pre-upgrade versions of the listed Python modules; inspect network traces for QUIC connections using ChaCha20-Poly1305 that exhibit unexpected packet loss or header anomalies on older NSS builds.

What your security team should do

• Prioritize upgrading all listed AlmaLinux 8 packages to the exact fixed versions within the next maintenance window
• Audit systems for Sandy Bridge processors still running older NSS-dependent components
• Monitor EPSS and any new exploit reports given the stable low score and absence from KEV