Описание
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.
A flaw was found in pyasn1, a generic ASN.1 library for Python. The Basic Encoding Rules (BER) decoder, used by CER and DER codecs, processes long-form tags by accumulating continuation octets without an upper bound. A remote attacker can exploit this by providing a specially crafted input, leading to the construction of an arbitrarily large integer. This can cause the CPU cost to grow quadratically, resulting in a Denial of Service (DoS) for any application decoding untrusted BER, CER, or DER input.
Отчет
A flaw was found in pyasn1's BER decoder. The decoder parses long-form tags by accumulating continuation octets without an upper bound, allowing crafted input to force construction of an arbitrarily large integer with quadratic CPU cost. On Python 3.11+, this can also trigger unhandled ValueError exceptions. Exploitation requires that an application passes untrusted BER, CER, or DER input directly to the pyasn1 decoder — pyasn1 is a library and does not independently accept network input. Many common uses of pyasn1 involve parsing trusted certificates or local configuration and are not exposed to this flaw. The realistic impact is a denial-of-service of the consuming Python process, with automatic recovery in typical service deployments.
Меры по смягчению последствий
Update to pyasn1 version 0.6.4 or later when available for your product stream. The impact is limited to availability (denial of service) — an attacker cannot access or modify data. Applications that do not process untrusted ASN.1/BER input are at reduced risk.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Exploit Intelligence | exploit-intelligence-tech-preview/vulnerability-analysis-rhel9 | Fix deferred | ||
| Lightspeed Core | lightspeed-core/lightspeed-stack-rhel9 | Fix deferred | ||
| Migration Toolkit for Applications 8 | mta/mta-rhel9-operator | Fix deferred | ||
| Migration Toolkit for Applications 8 | mta/mta-solution-server-rhel9 | Fix deferred | ||
| Migration Toolkit for Containers | rhmtc/openshift-migration-rhel8-operator | Fix deferred | ||
| Migration Toolkit for Virtualization | migration-toolkit-virtualization/mtv-rhel9-operator | Fix deferred | ||
| Migration Toolkit for Virtualization | mtv-candidate/mtv-rhel9-operator | Fix deferred | ||
| OpenShift Lightspeed | openshift-lightspeed/lightspeed-agentic-sandbox-rhel9 | Fix deferred | ||
| OpenShift Lightspeed | openshift-lightspeed/lightspeed-service-api-rhel9 | Fix deferred | ||
| OpenShift Lightspeed | openshift-lightspeed/lightspeed-to-dataverse-exporter-rhel9 | Fix deferred |
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Дополнительная информация
Статус:
EPSS
5.9 Medium
CVSS3
Связанные уязвимости
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.
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.
pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER ...
pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs
EPSS
5.9 Medium
CVSS3