Cyber Resilience

CVE-2021-40839

HighDDoS

Published: 10 September 2021

Published
10 September 2021
Modified
21 November 2024
KEV Added
—
Patch
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CVSS Score v3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.1729 95.2th percentile
Risk Priority 25 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-40839 is a high-severity Infinite Loop (CWE-835) vulnerability in Fedoraproject Fedora. Its CVSS base score is 7.5 (High).

Operationally, ranked in the top 4.8% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

The rencode package through 1.0.6 for Python allows an infinite loop in typecode decoding (such as via ;\x2f\x7f), enabling a remote attack that consumes CPU and memory.

CWE(s)
CWE-835

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

rencode project
rencode
≤ 1.0.6
fedoraproject
fedora
34, 35

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

CP-7 Alternate Processing Site
addresses: CWE-835

Enables transfer to alternate site if an infinite loop at the primary renders processing unavailable.

SC-5 Denial-of-service Protection
addresses: CWE-835

Detects and mitigates infinite loops that produce sustained resource consumption.

References