cryptography: PKCS#7 EnvelopedData decryption exposes a Bleichenbacher oracle through distinguishable errors and timing (CVE-2026-69247)
Description
A vulnerability in the python-cryptography library's PKCS#7 EnvelopedData decryption allows a Bleichenbacher oracle attack due to distinguishable errors and timing differences. This can potentially leak information during decryption operations. The issue is tracked as CVE-2026-69247 and affects multiple versions of the cryptography package. A patch is available to address this vulnerability.
CVSS v4.0
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-69247 describes a cryptographic vulnerability in the python-cryptography library where the PKCS#7 EnvelopedData decryption process exposes a Bleichenbacher oracle. This occurs because the decryption operation produces distinguishable error messages and timing variations that an attacker could exploit to gain information about the encrypted data. The vulnerability affects versions before 2.89.1-r2 and versions below 50.0.0, including exactly version 2.89.1-r2. The issue has been fixed in updated releases of the library.
Potential Impact
The vulnerability allows an attacker to perform a Bleichenbacher oracle attack by exploiting error and timing differences during PKCS#7 EnvelopedData decryption. This could lead to partial disclosure of plaintext or cryptographic keys under certain conditions. However, the attack requires high attack complexity and no privileges or user interaction, resulting in a medium severity rating.
Mitigation Recommendations
A patch is available for this vulnerability. Users should upgrade to a fixed version of the python-cryptography library that addresses CVE-2026-69247. Applying the official update will mitigate the risk of this Bleichenbacher oracle exposure.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- CLEANSTART-2026-ME02492
- Osv Schema Version
- 1.7.3
- Ecosystems
- ["Alpine"]
- State
- PUBLISHED
Threat ID: 6a984544acd9273b496aaf4d
Added to database: 09/02/2026, 15:48:20 UTC
Last enriched: 10/04/2026, 21:39:59 UTC
Last updated: 10/17/2026, 06:48:19 UTC
Views: 55
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