Malicious code in pystr-codec (PyPI)
Published Sources: OSV (Schadpakete)
- Malicious package
What is affected, what to do
Uninstall the package, isolate affected environments and rotate credentials that were available during installation.
Not sure whether and how you are affected? Ask a question about this vulnerability
Malicious package
PyPIpystr-codec
“pystr-codec” is registered as malicious in the PyPI repository. Anyone who installed the package should uninstall it immediately, isolate affected environments and rotate credentials that were present during installation.
Affected versions (3)
- 0.1.0
- 0.1.1
- 0.1.2
purl: pkg:pypi/pystr-codec
Sources (1)
kam193
pypi/2026-11-pystr-codec/pystr-codecVersions from this source: 0.1.0, 0.1.1, 0.1.2
sha256: 9f8b8630f88afc0b4a1aedeefb4e20adbf3fb9dea06f64747fb0bdf65c0a7bc1
The OSSF `malicious-packages` namespace lists packages flagged as malicious by static analysis or sandbox detonation. An entry here is a confirmed finding, not a suspicion.
Metrics
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Priority
No value is available for this vulnerability.
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CVSS v3
No value is available for this vulnerability.
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EPSS score
No value is available for this vulnerability.
Show all metrics
- Severity
- High
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 30.00 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
-= Per source details. Do not edit below this line.=-
Source: kam193 (9f8b8630f88afc0b4a1aedeefb4e20adbf3fb9dea06f64747fb0bdf65c0a7bc1)
Package embeds a malicious PTH file that on every Python startup executes obfuscated JavaScript code, using a Bun engine. It then exfiltrates credentials to a public Github repository, establishes persistence awaiting remote commands, attempts spreading using discovered credentials as well as periodically checks if discovered credentials are valid. Once they are invalidated, it performs destructive actions on the local machine. It seems to be part of the Miasma-family worm (also known under testmetest).
Category: MALICIOUS - The campaign has clearly malicious intent, like infostealers.
Campaign: 2026-11-pystr-codec
Reasons (based on the campaign):
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obfuscation
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abuses-pth
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infostealer
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worm
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backdoor
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persistence
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exfiltration-credentials
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destructive-actions