python-cryptography: Duplicate self-signed intermediates can cause exponential path-building
Noroxi assessment
Priority: Monitor (action score 34/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.25% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: pyca cryptography 49.0.0; azl3 python-cryptography 42.0.5-4 on Azure Linux 3.0 42.0.5-5.
Low priority for now. Upgrade to pyca cryptography 49.0.0; azl3 python-cryptography 42.0.5-4 on Azure Linux 3.0 42.0.5-5 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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.
- BDU:2026-11011
- EUVD-2026-52450
- GHSA-jwv3-5hgf-82ww
- ALSA-2026:64774
- ALSA-2026:64795
- ALSA-2026:71658
- openSUSE-SU-2026:21685-1
- PYSEC-2026-3553
- RHSA-2026:55543
- RHSA-2026:64774
- RHSA-2026:64795
- RHSA-2026:71658
- RHSA-2026:71659
- RLSA-2026:64774
- RLSA-2026:64795
- RLSA-2026:71658
- SUSE-SU-2026:23196-1
- SUSE-SU-2026:23247-1
- SUSE-SU-2026:23404-1
- SUSE-SU-2026:23570-1
- Published
- Aug 3, 2026
- Updated
- Sep 10, 2026
- EPSS
- 0.2% · 15th percentile
- CWE
- CWE-400
Report tools
Action score
34
Monitor
Low priority for now.
- CVSS
- 34 / 40 · 8.7 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.2%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · GitHub_M
- 8.7
- NVD has not scored this yet; the score shown is the CNA’s.
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
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
pyca cryptography
- >= 42.0.0, < 49.0.0affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:10 | python3-cryptography | before 43.0.0-4.el10_2.5 | 43.0.0-4.el10_2.5 |
| AlmaLinux:10 | python3.14-cryptography | before 45.0.4-4.el10_2.5 | 45.0.4-4.el10_2.5 |
| AlmaLinux:9 | python3.14-cryptography | before 45.0.4-4.el9_8.6 | 45.0.4-4.el9_8.6 |
| Debian:12 | python-cryptography | all versions | — |
| Debian:14 | python-cryptography | before 49.0.0-1 | 49.0.0-1 |
| openSUSE:Leap 16.0 | python-cryptography | before 44.0.3-160000.5.1 | 44.0.3-160000.5.1 |
| PyPI | cryptography | from 42.0.0 · before 49.0.0 | 49.0.0 |
| PyPI | cryptography | before 49.0.0 | 49.0.0 |
| Red Hat:enterprise_linux_eus:10.0 | python-cryptography | before 0:43.0.0-4.el10_0.1 | 0:43.0.0-4.el10_0.1 |
| Red Hat:enterprise_linux_eus:10.0 | python-cryptography-debugsource | before 0:43.0.0-4.el10_0.1 | 0:43.0.0-4.el10_0.1 |
| Red Hat:enterprise_linux_eus:10.0 | python3-cryptography | before 0:43.0.0-4.el10_0.1 | 0:43.0.0-4.el10_0.1 |
| Red Hat:enterprise_linux_eus:10.0 | python3-cryptography-debuginfo | before 0:43.0.0-4.el10_0.1 | 0:43.0.0-4.el10_0.1 |
| Red Hat:enterprise_linux:10.2 | python-cryptography | before 0:43.0.0-4.el10_2.5 | 0:43.0.0-4.el10_2.5 |
| Red Hat:enterprise_linux:10.2 | python-cryptography-debugsource | before 0:43.0.0-4.el10_2.5 | 0:43.0.0-4.el10_2.5 |
| Red Hat:enterprise_linux:10.2 | python3-cryptography | before 0:43.0.0-4.el10_2.5 | 0:43.0.0-4.el10_2.5 |
| Red Hat:enterprise_linux:10.2 | python3-cryptography-debuginfo | before 0:43.0.0-4.el10_2.5 | 0:43.0.0-4.el10_2.5 |
| Red Hat:enterprise_linux:10.2 | python3.14-cryptography | before 0:45.0.4-4.el10_2.5 | 0:45.0.4-4.el10_2.5 |
| Red Hat:enterprise_linux:10.2 | python3.14-cryptography-debuginfo | before 0:45.0.4-4.el10_2.5 | 0:45.0.4-4.el10_2.5 |
| Red Hat:enterprise_linux:10.2 | python3.14-cryptography-debugsource | before 0:45.0.4-4.el10_2.5 | 0:45.0.4-4.el10_2.5 |
| Red Hat:enterprise_linux:9::appstream | python3.14-cryptography | before 0:45.0.4-4.el9_8.6 | 0:45.0.4-4.el9_8.6 |
| Red Hat:enterprise_linux:9::appstream | python3.14-cryptography-debuginfo | before 0:45.0.4-4.el9_8.6 | 0:45.0.4-4.el9_8.6 |
| Red Hat:enterprise_linux:9::appstream | python3.14-cryptography-debugsource | before 0:45.0.4-4.el9_8.6 | 0:45.0.4-4.el9_8.6 |
| Red Hat:hummingbird:1 | python-cryptography | before 0:50.0.0-1.hum1 | 0:50.0.0-1.hum1 |
| Red Hat:hummingbird:1 | python3-cryptography | before 0:50.0.0-1.hum1 | 0:50.0.0-1.hum1 |
+6
Same product
pyca: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-69247cryptography: PKCS#7 EnvelopedData decryption exposes a Bleichenbacher oracle through distinguishable errors and timing32Monitor
- CVE-2026-69248python-cryptography verifier accepts wildcard DNS names allowing escape from permittedSubtrees27Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| pyca cryptography | 49.0.0 · description | Vendor (CNA) |
| azl3 python-cryptography 42.0.5-4 on Azure Linux 3.0 | 42.0.5-5 · CBL-Mariner Releases | Microsoft (MSRC) |
| almalinux:python3-cryptography | 43.0.0-4.el10_2.5 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:python3.14-cryptography | 45.0.4-4.el9_8.6 · AlmaLinux:9 | Package registry (OSV) |
| debian:python-cryptography | 49.0.0-1 · Debian:14 | Package registry (OSV) |
| opensuse:python-cryptography | 44.0.3-160000.5.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| PyPI:cryptography | 49.0.0 | Package registry (OSV) |
| red hat:python-cryptography | 0:50.0.0-1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:python-cryptography-debugsource | 0:43.0.0-4.el10_2.5 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:python3-cryptography | 0:50.0.0-1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:python3-cryptography-debuginfo | 0:43.0.0-4.el10_2.5 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:python3.14-cryptography | 0:45.0.4-4.el9_8.6 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:python3.14-cryptography-debuginfo | 0:45.0.4-4.el9_8.6 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:python3.14-cryptography-debugsource | 0:45.0.4-4.el9_8.6 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| rocky linux:python-cryptography | 0:43.0.0-4.el10_2.5 · Rocky Linux:10 | Package registry (OSV) |
| rocky linux:python3.14-cryptography | 0:45.0.4-4.el9_8.6 · Rocky Linux:9 | Package registry (OSV) |
| suse:python-cryptography | 42.0.4-slfo.1.1_6.1 · SUSE:Linux Micro 6.1 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- Integrity
- Availability
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- X
Weakness class (CWE)
CWE-400 · Uncontrolled Resource ConsumptionCVSS vector
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
nvd-secondary
Root cause
Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.
The bug in code
The whole CWE-400 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
function expand(node) { return node.children.map(expand);}Fixed
const MAX_DEPTH = 32;function expand(node, depth = 0) { if (depth > MAX_DEPTH) throw new Error("too deep"); return node.children.map((c) => expand(c, depth + 1));}Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (4 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.