pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs
Priority MEDIUM 40CWE-400Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 7 fixed, 29 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.
Summary
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00616 49th percentileScored 2026-11-07
Fix Partial pyasn1 (pyasn1): 0.6.4pyasn1 (PyPI): 0.6.4Red Hat: 9 advisoriesRed Hat: 7 fixed, 29 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| pyasn1 | pyasn1 | before 0.6.4 | 0.6.4 | Patch available | CNA |
| — | pyasn1 (PyPI) | before 0.6.4 | 0.6.4 | Patch available | GHSA-m4p7-r5rc-7g4j |
- pyasn1 Vendorpyasn1 Affected before 0.6.4 Fixed in 0.6.4 Patch available CNA
- pyasn1 (PyPI) Vendor— Affected before 0.6.4 Fixed in 0.6.4 Patch available GHSA-m4p7-r5rc-7g4j
Remediation
- Fix · CNA pyasn1 (pyasn1) Fixed in 0.6.4
- Fix · GHSA-m4p7-r5rc-7g4j pyasn1 (PyPI) Fixed in 0.6.4 Advisory →
Red Hat 9 advisories
- RHSA-2026:87410 Released 2026-10-21 · Red Hat rating CriticalRHOAI 2.25.12 - Red Hat OpenShift AI
- Red Hat OpenShift AI 2.25 registry.redhat.io/rhoai/odh-built-in-detector-rhel9, registry.redhat.io/rhoai/odh-caikit-nlp-rhel9, registry.redhat.io/rhoai/odh-codeflare-operator-rhel9 +47
- RHSA-2026:84734 Released 2026-10-19 · Red Hat rating CriticalRHOAI 3.4.5 - Red Hat OpenShift AI
- Red Hat OpenShift AI 3.4 registry.redhat.io/rhoai/odh-ai-gateway-payload-processing-rhel9, registry.redhat.io/rhoai/odh-automl-rhel9, registry.redhat.io/rhoai/odh-autorag-rhel9 +47
- RHSA-2026:83121 Released 2026-10-14 · Red Hat rating ImportantRed Hat AI Inference 3.4.6 (rocm)
- Red Hat AI Inference Server 3.4 registry.redhat.io/rhaii/vllm-rocm-rhel9
Show 6 more Red Hat advisories
- RHSA-2026:73987 Released 2026-09-30 · Red Hat rating CriticalRHOAI 3.3.7 - Red Hat OpenShift AI
- Red Hat OpenShift AI 3.3 registry.redhat.io/rhoai/odh-built-in-detector-rhel9, registry.redhat.io/rhoai/odh-dashboard-rhel9, registry.redhat.io/rhoai/odh-data-science-pipelines-argo-argoexec-rhel9 +47
- RHSA-2026:62336 Released 2026-09-01 · Red Hat rating ImportantRed Hat Enterprise Linux AI 3.3.6 enhancement update
- Red Hat Enterprise Linux AI 3.3 registry.redhat.io/rhelai3/bootc-aws-cuda-rhel9, registry.redhat.io/rhelai3/bootc-azure-cuda-rhel9, registry.redhat.io/rhelai3/bootc-azure-rocm-rhel9 +3
- RHSA-2026:62335 Released 2026-09-01 · Red Hat rating ImportantRed Hat Enterprise Linux AI 3.3.6 enhancement update
- Red Hat Enterprise Linux AI 3.3 registry.redhat.io/rhelai3/disk-image-cuda-rhel9
- RHSA-2026:60520 Released 2026-08-27 · Red Hat rating CriticalRHOAI 3.4.4 - Red Hat OpenShift AI
- Red Hat OpenShift AI 3.4 registry.redhat.io/rhoai/odh-automl-rhel9, registry.redhat.io/rhoai/odh-autorag-rhel9, registry.redhat.io/rhoai/odh-built-in-detector-rhel9 +47
- RHSA-2026:59518 Released 2026-08-25 · Red Hat rating ImportantRed Hat AI Inference Server Model Optimization Tools 3.3.6 (CUDA)
- Red Hat AI Inference Server 3.3 registry.redhat.io/rhaiis/model-opt-cuda-rhel9
- RHSA-2026:40236 Released 2026-07-15 · Red Hat rating ImportantRed Hat Hardened Images RPMs Security Update
- Red Hat Hardened Images jaeger-2.19.0-1.1.hum1@aarch64, jaeger-2.19.0-1.1.hum1@src, jaeger-2.19.0-1.1.hum1@x86_64
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Exploit Intelligence | Affected | No fix yet: Fix deferred |
| Lightspeed Core | Affected | No fix yet: Fix deferred |
| Migration Toolkit for Applications 8 | Affected | No fix yet: Fix deferred |
| Migration Toolkit for Containers | Affected | No fix yet: Fix deferred |
| Migration Toolkit for Virtualization | Affected | No fix yet: Fix deferred |
| OpenShift Lightspeed | Affected | No fix yet: Fix deferred |
| OpenShift Service Mesh 3 | Affected | No fix yet: Fix deferred |
| Red Hat AI Inference Server | Affected | No fix yet |
| Red Hat Advanced Cluster Management for Kubernetes 2 | Affected | No fix yet: Fix deferred |
| Red Hat Ansible Automation Platform 2 | Affected | No fix yet: Fix deferred |
| Red Hat Ceph Storage 7 | Affected | No fix yet: Fix deferred |
| Red Hat Ceph Storage 8 | Affected | No fix yet: Fix deferred |
| Red Hat Ceph Storage 9 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
| Red Hat OpenStack Platform 16.2 | Affected | No fix yet: Fix deferred |
| Red Hat OpenStack Platform 17.1 | Affected | No fix yet: Fix deferred |
| Red Hat OpenStack Platform 18.0 | Affected | No fix yet: Fix deferred |
| Red Hat Quay 3 | Affected | No fix yet: Fix deferred |
| Red Hat Satellite 6 | Affected | No fix yet: Fix deferred |
| Red Hat Trusted Artifact Signer | Affected | No fix yet: Fix deferred |
| Service Telemetry Framework 1.5 | Affected | No fix yet: Fix deferred |
| Red Hat AI Inference Server 3.3 | Fixed | RHSA-2026:59518 |
| Red Hat AI Inference Server 3.4 | Fixed | RHSA-2026:83121 |
| Red Hat Enterprise Linux AI 3.3 | Fixed | RHSA-2026:62335, RHSA-2026:62336 |
| Red Hat Hardened Images | Fixed | RHSA-2026:40236 |
| Red Hat OpenShift AI 2.25 | Fixed | RHSA-2026:87410 |
| Red Hat OpenShift AI 3.3 | Fixed | RHSA-2026:73987 |
| Red Hat OpenShift AI 3.4 | Fixed | RHSA-2026:60520, RHSA-2026:84734 |
Not affected: 6 products
- Red Hat Enterprise Linux AI 3.3
- Red Hat Hardened Images
- Red Hat OpenShift AI (RHOAI)
- Red Hat OpenShift AI 2.25
- Red Hat OpenShift AI 3.3
- Red Hat OpenShift AI 3.4
Timeline
- 2026-10-02 Threatist record created from CVE-2026-59884
- 2026-10-03 Alias added: GHSA-m4p7-r5rc-7g4j
- 2026-10-07 Fix available: RHSA-2026:73987 · Red Hat
- 2026-10-16 Fix available: RHSA-2026:83121 · Red Hat
- 2026-10-16 Fix available: Red Hat AI Inference Server 3.4 · Red Hat
- 2026-10-20 Fix available: RHSA-2026:84734 · Red Hat
- 2026-10-20 Affected versions changed · Red Hat
- 2026-10-22 Fix available: RHSA-2026:87410 · Red Hat
- 2026-10-23 Fix available: Red Hat OpenShift AI 2.25 · Red Hat
- 2026-10-30 Affected versions changed · Red Hat
References
Advisory 2
More Pyasn1 vulnerabilities
- TI-2026-23747 pyasn1 Vulnerable to Denial of Service via Unbounded Recursion CVSS 3.1HIGH 7.5
- TI-2026-18923 pyasn1 has a DoS vulnerability in decoder CVSS 3.1HIGH 7.5
- TI-2026-42699 pyasn1: Quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of service CVSS 3.1HIGH 7.5
- TI-2026-42700 pyasn1: Uncontrolled resource consumption when converting decoded REAL values CVSS 3.1HIGH 7.5
Sources
- CVE-2026-59884 · CVE Program
- CVE-2026-59884 · NVD
- FIRST EPSS
- GHSA-m4p7-r5rc-7g4j · GitHub Advisory Database · CC BY 4.0
- CVE-2026-59884 · Red Hat security data · CC BY 4.0
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