CVE-2026-69249 pyca CVE debrief

Who should care

Developers and administrators using python-cryptography versions 42.0.0 through 48.0.0 should be aware of the potential for resource exhaustion denial of service attacks and take steps to mitigate the issue. This includes upgrading to version 49.0.0 or later and reviewing affected systems and dependencies. Organizations should prioritize upgrading to version 49.0.0 to mitigate potential resource exhaustion denial of service attacks. Additionally, users should monitor for potential resource exhaustion attacks and review compensating controls for exposed systems while remediation is scheduled and verified. Asset inventory and vulnerability management teams should also be informed to ensure proper tracking and remediation of affected systems. Security teams should review the vulnerability details and assess the impact on their organization's assets and systems. They should also verify that the upgrade to version 49.0.0 or later has been successfully implemented and that affected systems are properly patched. Furthermore, users should check relevant monitoring, detection, and logs for exposed assets that need extra review and track exceptions, retest remediated assets, and close the item only after evidence is documented. This comprehensive approach will help ensure that the vulnerability is properly addressed and that the risk of resource exhaustion denial of service attacks is minimized. It is also essential to confirm whether affected product deployments exist in managed environments and assign an owner for follow-up to guarantee a timely and effective remediation process. Finally, reviewing the supplied official advisory or CVE record will help validate affected scope, severity, and vendor guidance, ensuring that all necessary steps are taken to mitigate the vulnerability effectively. In cases where immediate remediation is not feasible, compensating controls should be implemented and verified to reduce the risk of exploitation. By taking these steps, organizations can effectively manage the risk associated with this vulnerability and protect their systems from potential resource exhaustion denial of service attacks. The CVE record was published on 2026-08-03T22

Technical summary

The python-cryptography package, versions 42.0.0 through 48.0.0, is vulnerable to a resource exhaustion denial of service attack due to recursive processing of invalid certificate chains with duplicate self-signed certificates. The issue arises from the recursive nature of build_chain_inner, which does not de-duplicate against previously analyzed candidates. This leads to an exponential blowup in processing, potentially causing resource exhaustion. The vulnerability has a CVSS score of 8.7 and is considered HIGH severity. The issue is fixed in version 49.0.0.

Defensive priority

Organizations using python-cryptography versions 42.0.0 through 48.0.0 should prioritize upgrading to version 49.0.0 to mitigate potential resource exhaustion denial of service attacks.

Recommended defensive actions

• Upgrade to python-cryptography version 49.0.0 or later
• Review and update affected systems and dependencies
• Monitor for potential resource exhaustion attacks
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE-2026-69249 issue arises from the recursive nature of build_chain_inner in python-cryptography, which does not de-duplicate against previously analyzed candidates, leading to potential resource exhaustion. The issue is fixed in version 49.0.0.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.