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python-cryptography EUVDEUVD-2026-52450

| CVE-2026-69249 HIGH
Uncontrolled Resource Consumption (CWE-400)
2026-08-03 GitHub_M GHSA-jwv3-5hgf-82ww
Denial Of Service Python Cryptography Pyca
8.7
CVSS 4.0 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
8.7 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
7.5 HIGH

Unauthenticated network submission of certificate chains triggers CPU exhaustion with no confidentiality or integrity impact, scoped to the vulnerable system only.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
5.3 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

4
Patch available
Aug 03, 2026 - 22:17 EUVD
Source Code Evidence Fetched
Aug 03, 2026 - 22:06 vuln.today
Analysis Generated
Aug 03, 2026 - 22:06 vuln.today
CVE Published
Aug 03, 2026 - 21:26 cve.org
HIGH 8.7

Blast Radius

ecosystem impact
† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth
  • 12 pypi packages depend on cryptography (11 direct, 1 indirect)

Ecosystem-wide dependent count for version 42.0.0.

DescriptionCVE.org

python-cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. Prior to 49.0.0, 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.

Articles & Coverage 2

News 3 New Python Vulnerabilities - 3 High Severity, 3 With POC Aug 04, 2026 News 3 New Python Vulnerabilities - 3 High Severity, 1 With POC Aug 03, 2026

AnalysisAI

Certificate path building in python-cryptography before 49.0.0 is exploitable as a denial-of-service vector by attackers who can supply crafted X.509 chains containing duplicate self-signed intermediate certificates. The Rust-based build_chain_inner function explores issuer candidates recursively without deduplicating previously analyzed entries, causing computational work to grow exponentially with the number of duplicates present - empirically exceeding 5 seconds per rejection in testing. No active exploitation has been confirmed (not in CISA KEV) and no public exploit code has been identified; the fix shipped in 49.0.0 bounds path-building via a global signature-check budget.

Technical ContextAI

The vulnerable component is the Rust x509-verification crate (cryptography-x509-verification) embedded within the pyca/cryptography Python package, which implements RFC 5280 certificate path validation. CWE-400 (Uncontrolled Resource Consumption) manifests in build_chain_inner: each call to potential_issuers collects all candidate issuers without filtering previously visited ones, so duplicate self-signed certificates in the untrusted intermediate set cause the recursion tree to branch exponentially at each depth level. Although the max_chain_depth policy cap guarantees eventual termination, the exponential fan-out within that bound is sufficient for a DoS amplification. CPE cpe:2.3:a:pyca:cryptography:*:*:*:*:*:*:*:* covers all versions through 48.0.0. The fix (PR #14960, commit 4a12cf49) introduces a global signature-check budget defaulting to 128 operations - matching Go's and rustls-webpki's defaults - and adds AKI/SKI-based candidate ordering to prioritize likely issuers and preserve budget efficiency.

RemediationAI

Upgrade the cryptography package to version 49.0.0 or later via pip install --upgrade cryptography, which introduces the 128-operation signature-check budget that bounds worst-case path-building cost regardless of input structure; this is the only confirmed fix. The upstream patch is in commit 4a12cf49675a184e47f912b00b04f3a629283582 and pull request https://github.com/pyca/cryptography/pull/14960. If immediate upgrade is blocked, the most effective compensating control is to restrict the application so it never passes externally supplied intermediate certificates to the path validator - for example, by disabling TLS client certificate verification, enforcing that all intermediates are sourced from a pinned internal store, or validating chain uniqueness at the application boundary before invocation. These workarounds are fragile and operationally costly; they do not eliminate the root cause and should be treated as temporary bridges to patching.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Not-Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Not-Affected
SUSE Linux Enterprise Micro 5.3 Not-Affected

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EUVD-2026-52450 vulnerability details – vuln.today
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