vulnerability / NVI-00013016 / Revision 2
python-cryptography: Duplicate self-signed intermediates can cause exponential path-building
GitHub lists this reviewed advisory for cryptography. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
8.7 HIGH (4.0)
security-advisories@github.com severity; no combined Null risk score.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
cryptography
source listed>= 42.0.0, < 49.0.0
### Summary 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. This work was completed by Trail of Bits as part of the Patch The Planet project in collaboration with OpenAI. The finding was identified primarily by the Codex coding agent, and manually reviewed before submission. ### Details The core issue arises in the recursive nature of `build_chain_inner`, which does not de-duplicate against previously analyzed candidates. ```python fn build_chain_inner( &self, working_cert: &VerificationCertificate, current_depth: u8, working_cert_extensions: &Extensions, name_chain: NameChain, budget: &mut Budget, ) -> Validat
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. NIST National Vulnerability Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
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05 / Provenance
Sources you can inspect
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- GHSA-jwv3-5hgf-82ww ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-69249 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
Public revision history
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- Revision 2 ·
Source facts changed; compare the preserved prior revision.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.