CVE-2026-69249: CWE-400: Uncontrolled Resource Consumption in pyca cryptography
python-cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. In versions 42.0.0 through 48.0.0, when resolving invalid certificate chains that include duplicate copies of self-signed certificates, the processing recursively invokes the same candidate, leading to an exponential blowup. Although the limitation that the chain depth cannot exceed a specified maximum depth prevents unbounded recursion and guarantees termination, an attacker-controlled certificate chain can lead the processing to easily take more than 5s to reject in testing. This amplification could form the basis for a resource exhaustion denial of service attack. The core issue arises in the recursive nature of build_chain_inner, which does not de-duplicate against previously analyzed candidates. As the correctness of validation is not affected, the integrity of a system cannot be compromised through this vector, only its availability. This issue is fixed in 49.0.0.
AI Analysis
Technical Summary
The python-cryptography package before version 49.0.0 has a vulnerability where resolving invalid certificate chains with duplicate self-signed certificates causes recursive invocation of the same candidate in the build_chain_inner function. This recursion leads to exponential blowup in processing time, potentially exceeding 5 seconds to reject such chains. Although a maximum chain depth prevents unbounded recursion, the amplification effect can be exploited for denial of service attacks. The vulnerability does not compromise cryptographic validation correctness or system integrity. The issue is addressed in version 49.0.0.
Potential Impact
An attacker can craft a certificate chain with duplicate self-signed certificates that causes the cryptography package to consume excessive CPU resources during validation. This results in a denial of service condition by slowing or blocking the processing of certificate chains. The vulnerability affects system availability but does not impact confidentiality, integrity, or authentication.
Mitigation Recommendations
A fix is available in python-cryptography version 49.0.0. Users should upgrade to version 49.0.0 or later to remediate this vulnerability. No other vendor advisory or temporary workaround is provided.
CVE-2026-69249: CWE-400: Uncontrolled Resource Consumption in pyca cryptography
Description
python-cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. In versions 42.0.0 through 48.0.0, when resolving invalid certificate chains that include duplicate copies of self-signed certificates, the processing recursively invokes the same candidate, leading to an exponential blowup. Although the limitation that the chain depth cannot exceed a specified maximum depth prevents unbounded recursion and guarantees termination, an attacker-controlled certificate chain can lead the processing to easily take more than 5s to reject in testing. This amplification could form the basis for a resource exhaustion denial of service attack. The core issue arises in the recursive nature of build_chain_inner, which does not de-duplicate against previously analyzed candidates. As the correctness of validation is not affected, the integrity of a system cannot be compromised through this vector, only its availability. This issue is fixed in 49.0.0.
CVSS v4.0
Score 8.7high
Affected software
pyca
cryptography
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The python-cryptography package before version 49.0.0 has a vulnerability where resolving invalid certificate chains with duplicate self-signed certificates causes recursive invocation of the same candidate in the build_chain_inner function. This recursion leads to exponential blowup in processing time, potentially exceeding 5 seconds to reject such chains. Although a maximum chain depth prevents unbounded recursion, the amplification effect can be exploited for denial of service attacks. The vulnerability does not compromise cryptographic validation correctness or system integrity. The issue is addressed in version 49.0.0.
Potential Impact
An attacker can craft a certificate chain with duplicate self-signed certificates that causes the cryptography package to consume excessive CPU resources during validation. This results in a denial of service condition by slowing or blocking the processing of certificate chains. The vulnerability affects system availability but does not impact confidentiality, integrity, or authentication.
Mitigation Recommendations
A fix is available in python-cryptography version 49.0.0. Users should upgrade to version 49.0.0 or later to remediate this vulnerability. No other vendor advisory or temporary workaround is provided.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-03T19:54:19.852Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a710cc4bf32cb7a3449087d
Added to database: 08/03/2026, 21:48:52 UTC
Last enriched: 08/11/2026, 18:38:08 UTC
Last updated: 09/17/2026, 22:01:37 UTC
Views: 58
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