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Fencer Vulns
high 7.5

CVE-2026-59886 json

pyasn1: Uncontrolled resource consumption when converting decoded REAL values

published 2026-07-14 3 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-43738 , GHSA-hm4w-wwcw-mr6r , PYSEC-2026-3457

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the univ.Real type converted its mantissa, base, and exponent value to a Python float using exact big-integer exponentiation. A BER, CER, or DER encoded REAL value only a few bytes long can carry a very large exponent, causing float conversion through prettyPrint(), str(), comparison, arithmetic, int(), or an explicit float() call to consume excessive CPU and memory and hang applications that decode untrusted ASN.1 data and then print, log, or compare decoded objects. This issue is fixed in version 0.6.4.

Patch / fix

  • pypi pyasn1 0.6.4
  • pyasn1 pyasn1 0.6.4
  • pyasn1 Debian 12 0.4.8-3+deb12u3
  • pyasn1 Debian 13 0.6.1-1+deb13u3
  • pyasn1 Debian 14 0.6.4-1

debian advisories DEBIAN-CVE-2026-59886

  • pyasn1 Ubuntu 22.04 LTS 0.4.8-1ubuntu0.3
  • pyasn1 Ubuntu 24.04 LTS 0.4.8-4ubuntu0.3
  • pyasn1 Ubuntu 26.04 LTS 0.6.3-1ubuntu0.1

ubuntu advisories UBUNTU-CVE-2026-59886

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • resource-agents RHEL 7 EXTRAS_SAP_HANA_ELS, RHEL 7 EXTRAS_SAP_ELS, RHEL 7 4.1.1-61.el7_9.24
  • resource-agents-gcp RHEL 7 4.1.1-61.el7_9.24
  • resource-agents-aliyun RHEL 7 4.1.1-61.el7_9.24
  • python-pyasn1 RHEL 10.2 0.6.2-1.el10_2.1
  • python3-pyasn1 RHEL 10.2 0.6.2-1.el10_2.1
  • python3-pyasn1-modules RHEL 10.2 0.6.2-1.el10_2.1
  • python-pyasn1 RHEL 8 0.3.7-6.el8_10.2
  • python3-pyasn1 RHEL 8 0.3.7-6.el8_10.2

red hat advisories RHSA-2026:59329RHSA-2026:59247RHSA-2026:59248RHSA-2026:59245RHSA-2026:59246RHSA-2026:59243

  • python-pyasn1 Linux Micro 6.1 0.5.0-slfo.1.1_4.1
  • python-pyasn1 Linux Micro 6.0 0.5.0-5.1
  • python-pyasn1 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +9 more 0.5.0-150400.12.16.1
  • python-pyasn1 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 0.6.1-160000.5.1

suse advisories SUSE-SU-2026:23167-1SUSE-SU-2026:23006-1SUSE-SU-2026:3238-1SUSE-SU-2026:22765-1SUSE-SU-2026:22830-1

  • python-pyasn1 openSUSE Leap 16.0 0.6.1-160000.5.1
  • python-pyasn1 openSUSE Tumbleweed 0.6.4-1.1

opensuse advisories openSUSE-SU-2026:21392-1openSUSE-SU-2026:11318-1

  • python3-pyasn1 AlmaLinux 8 0.3.7-6.el8_10.2
  • python3-pyasn1-modules AlmaLinux 8 0.3.7-6.el8_10.2
  • python3-pyasn1 AlmaLinux 9 0.4.8-7.el9_8.1
  • python3-pyasn1-modules AlmaLinux 9 0.4.8-7.el9_8.1
  • python3-pyasn1 AlmaLinux 10 0.6.2-1.el10_2.1
  • python3-pyasn1-modules AlmaLinux 10 0.6.2-1.el10_2.1
  • fence-agents-all AlmaLinux 8 4.2.1-129.el8_10.29
  • fence-agents-apc AlmaLinux 8 4.2.1-129.el8_10.29

almalinux advisories ALSA-2026:59241ALSA-2026:59242ALSA-2026:59243ALSA-2026:53363ALSA-2026:53364ALSA-2026:53365

  • python-pyasn1 Rocky Linux 10 0.6.2-1.el10_2.1
  • python-pyasn1 Rocky Linux 9 0.4.8-7.el9_8.1
  • python-pyasn1 Rocky Linux 8 0.3.7-6.el8_10.2
  • fence-agents Rocky Linux 9 4.10.0-110.el9_8.6
  • resource-agents Rocky Linux 8 4.9.0-54.el8_10.37
  • fence-agents Rocky Linux 8 4.2.1-129.el8_10.29

rocky linux advisories RLSA-2026:59243RLSA-2026:59242RLSA-2026:59241RLSA-2026:53365RLSA-2026:53364RLSA-2026:53363

  • python-pyasn1 Azure Linux 3.0 0.4.8-3

azure linux advisories AZL-92436

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-59886 updated cvss 7.5

pyasn1: pyasn1: Denial of Service via crafted ASN.1 REAL values

  • Red Hat Exploit Intelligence exploit-intelligence-tech-preview/vulnerability-analysis-rhel9
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Lightspeed Core lightspeed-core/lightspeed-stack-rhel9
    affected: workaround, no fix available
  • Red Hat Migration Toolkit for Containers rhmtc/openshift-migration-rhel8-operator
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Migration Toolkit for Virtualization mtv-candidate/mtv-rhel9-operator, migration-toolkit-virtualization/mtv-rhel9-operator
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-service-api-rhel9, openshift-lightspeed/lightspeed-agentic-sandbox-rhel9, openshift-lightspeed/lightspeed-to-dataverse-exporter-rhel9
    affected: workaround, no fix available
  • Red Hat AI Inference Server rhaii/vllm-tpu-rhel9, rhaiis/vllm-tpu-rhel9, rhaiis/vllm-rocm-rhel9 Red Hat Ansible Automation Platform 2 ansible-automation-platform-26/hub-rhel9, ansible-automation-platform-27/hub-rhel9, ansible-automation-platform-24/lightspeed-rhel8, ansible-automation-platform-26/controller-rhel9, ansible-automation-platform-27/controller-rhel9, ansible-automation-platform-25/ee-supported-rhel8, +15 more
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat Ceph Storage 7 rhceph/rhceph-7-rhel9 Red Hat Ceph Storage 8 rhceph/rhceph-8-rhel9 Red Hat Ceph Storage 9 rhceph/rhceph-9-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 python-pyasn1 0.0.12a-1.el6
    affected: workaround, no fix planned “Out of support scope”
show 21 more
  • Red Hat Enterprise Linux 9 rhel9/keylime-verifier, rhel9/keylime-registrar Red Hat Enterprise Linux 10 fence-agents-common, rhel10/keylime-verifier, rhel10/keylime-registrar Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-rocm-rhel9, rhelai3/bootc-azure-rocm-rhel9 Red Hat OpenShift AI (RHOAI) rhoai/odh-pipelines-components-rhel9, rhoai/odh-ml-pipelines-runtime-generic-rhel9, rhoai/odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9 Red Hat OpenStack Platform 16.2 python3-pyasn1, python3-pyasn1-modules, python-pyasn1 0.0.12a-1.el6 Red Hat OpenStack Platform 17.1 python-pyasn1 0.0.12a-1.el6
    +2 more products
    Red Hat OpenStack Platform 18.0 rhoso-operators/ee-openstack-ansible-ee-rhel9 Red Hat Satellite 6 python3.12-pyasn1, python-pyasn1-modules, python3.12-pyasn1-modules, python-pyasn1 0.0.12a-1.el6, satellite/iop-advisor-engine-rhel9
    affected: workaround, no fix available
  • Red Hat AI Inference Server 3.3 rhaiis/model-opt-cuda-rhel9 1787601159
    fixed: vendor fix RHSA-2026:59518
  • Red Hat AI Inference Server 3.4 rhaii/vllm-rocm-rhel9 1791856725
    fixed: vendor fix RHSA-2026:83121
  • Red Hat Ansible Automation Platform 2.5 ansible-automation-platform-25/lightspeed-rhel8 1787229385
    fixed: vendor fix RHSA-2026:59159
  • Red Hat Ansible Automation Platform 2.5 for RHEL 8 python3.12-pyasn1 0.6.4-1.el8ap, automation-controller-venv-tower 4.6.32-1.el8ap Red Hat Ansible Automation Platform 2.5 for RHEL 9 python3.12-pyasn1 0.6.4-1.el9ap, automation-controller-venv-tower 4.6.32-1.el9ap
    fixed: vendor fix RHSA-2026:59135
  • Red Hat Ansible Automation Platform 2.6 ansible-automation-platform-26/gateway-rhel9 1787219751, ansible-automation-platform-26/lightspeed-rhel9 1785775360, ansible-automation-platform-26/eda-controller-rhel9 1787021043, ansible-automation-platform-26/lightspeed-chatbot-rhel9 1785646188
    fixed: vendor fix RHSA-2026:59155
  • Red Hat Ansible Automation Platform 2.6 for RHEL 9 python3.12-pyasn1 0.6.4-1.el9ap, automation-controller-venv-tower 4.7.16-1.el9ap
    fixed: vendor fix RHSA-2026:59136
  • Red Hat Ansible Automation Platform 2.7 ansible-automation-platform-27/gateway-rhel9 1787218409, ansible-automation-platform-27/lightspeed-rhel9 1787217531, ansible-automation-platform-27/ee-supported-rhel9 1787235693, ansible-automation-platform-27/eda-controller-rhel9 1787163758, ansible-automation-platform-27/lightspeed-chatbot-rhel9 1785426734
    fixed: vendor fix RHSA-2026:59153
  • Red Hat Enterprise Linux AI 3.3 rhelai3/bootc-cuda-rhel9 1788260684, rhelai3/bootc-aws-cuda-rhel9 1788273908, rhelai3/bootc-gcp-cuda-rhel9 1788273977, rhelai3/disk-image-cuda-rhel9 1788290314, rhelai3/bootc-azure-cuda-rhel9 1788273909
    fixed: vendor fix RHSA-2026:62336
  • Red Hat Enterprise Linux AppStream (v. 8) python-pyasn1 0.3.7-6.el8_10.2, python3-pyasn1 0.3.7-6.el8_10.2, fence-agents 4.2.1-129.el8_10.29, fence-agents-all 4.2.1-129.el8_10.29, fence-agents-apc 4.2.1-129.el8_10.29, fence-agents-eps 4.2.1-129.el8_10.29, +41 more
    fixed: vendor fix RHSA-2026:53363
  • Red Hat Enterprise Linux AppStream (v. 9) fence-virt 4.10.0-110.el9_8.6, python-pyasn1 0.4.8-7.el9_8.1, fence-virtd 4.10.0-110.el9_8.6, python3-pyasn1 0.4.8-7.el9_8.1, fence-agents 4.10.0-110.el9_8.6, fence-virtd-cpg 4.10.0-110.el9_8.6, +54 more
    fixed: vendor fix RHSA-2026:53365
  • Red Hat Enterprise Linux AppStream (v. 10) python-pyasn1 0.6.2-1.el10_2.1, python3-pyasn1 0.6.2-1.el10_2.1, python3-pyasn1-modules 0.6.2-1.el10_2.1
    fixed: vendor fix RHSA-2026:59243
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) python-pyasn1 0.3.7-6.el8_4.2, fence-agents 4.2.1-65.el8_4.32, python3-pyasn1 0.3.7-6.el8_4.2, fence-agents-all 4.2.1-65.el8_4.32, fence-agents-apc 4.2.1-65.el8_4.32, fence-agents-eps 4.2.1-65.el8_4.32, +40 more
    fixed: vendor fix RHSA-2026:58821
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) python-pyasn1 0.3.7-6.el8_6.2, fence-agents 4.2.1-89.el8_6.26, python3-pyasn1 0.3.7-6.el8_6.2, fence-agents-all 4.2.1-89.el8_6.26, fence-agents-apc 4.2.1-89.el8_6.26, fence-agents-eps 4.2.1-89.el8_6.26, +40 more
    fixed: vendor fix RHSA-2026:58835
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) python-pyasn1 0.3.7-6.el8_8.2, python3-pyasn1 0.3.7-6.el8_8.2, fence-agents 4.2.1-112.el8_8.21, fence-agents-all 4.2.1-112.el8_8.21, fence-agents-apc 4.2.1-112.el8_8.21, fence-agents-eps 4.2.1-112.el8_8.21, +40 more
    fixed: vendor fix RHSA-2026:58822
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) fence-virt 4.10.0-43.el9_2.25, python-pyasn1 0.4.8-6.el9_2.2, fence-virtd 4.10.0-43.el9_2.25, python3-pyasn1 0.4.8-6.el9_2.2, fence-agents 4.10.0-43.el9_2.25, fence-virtd-cpg 4.10.0-43.el9_2.25, +11 more
    fixed: vendor fix RHSA-2026:58546
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) fence-virt 4.10.0-62.el9_4.29, python-pyasn1 0.4.8-6.el9_4.2, fence-virtd 4.10.0-62.el9_4.29, python3-pyasn1 0.4.8-6.el9_4.2, fence-agents 4.10.0-62.el9_4.29, fence-virtd-cpg 4.10.0-62.el9_4.29, +11 more
    fixed: vendor fix RHSA-2026:58547
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) python-pyasn1 0.6.2-1.el10_0.2, python3-pyasn1 0.6.2-1.el10_0.2, python3-pyasn1-modules 0.6.2-1.el10_0.2
    fixed: vendor fix RHSA-2026:59238
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) fence-virt 4.10.0-86.el9_6.21, python-pyasn1 0.4.8-6.el9_6.2, fence-virtd 4.10.0-86.el9_6.21, python3-pyasn1 0.4.8-6.el9_6.2, fence-agents 4.10.0-86.el9_6.21, fence-virtd-cpg 4.10.0-86.el9_6.21, +54 more
    fixed: vendor fix RHSA-2026:58548
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) python-pyasn1 0.3.7-6.el8_4.2, fence-agents 4.2.1-65.el8_4.32, python3-pyasn1 0.3.7-6.el8_4.2, fence-agents-all 4.2.1-65.el8_4.32, fence-agents-apc 4.2.1-65.el8_4.32, fence-agents-eps 4.2.1-65.el8_4.32, +36 more
    fixed: vendor fix RHSA-2026:58821
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) python-pyasn1 0.3.7-6.el8_6.2, fence-agents 4.2.1-89.el8_6.26, python3-pyasn1 0.3.7-6.el8_6.2, fence-agents-all 4.2.1-89.el8_6.26, fence-agents-apc 4.2.1-89.el8_6.26, fence-agents-eps 4.2.1-89.el8_6.26, +40 more
    fixed: vendor fix RHSA-2026:58835

35 more fixed, 31 more not affected in the full advisory

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi pyasn1
<0.6.4
0.6.4

Affected products

  • pyasn1 pyasn1

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.