Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2021-40839

27
FAUCET Score

CVE-2021-40839 is a high-severity vulnerability affecting the rencode Python package (through version 1.0.6) and related Fedora products. It allows an unauthenticated remote attacker to trigger an infinite loop during typecode decoding, leading to a denial-of-service condition by consuming CPU and memory resources. While the CVSS score is 7.5, indicating a significant impact, there is currently no public exploit code available, nor is there evidence of active exploitation or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.0.6CPE matchmatch criteria
cpe:2.3:a:rencode_project:rencode:*:*:*:*:*:python:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
35CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
5.57%
Probability of exploitation in next 30 days
EPSS Percentile
92.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0557 is in the 86th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

pipGHSA-gh8j-2pgf-x458high

Infinite Loop in rencode

Sep 13, 2021

References

github.com / aresch/rencode/commit/572ff74586d9b1daab904c6f7f7009ce0143bb75
PatchThird Party Advisory
github.com / aresch/rencode/pull/29
PatchThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/BMVQRPDVSVZNGGX57CFKCYT3DEYO4QB6
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/MCLETLGVM5DBX6QNHQFW6TWGO5T3DENY
pypi.org / project/rencode
Third Party Advisory
seclists.org / fulldisclosure/2021/Sep/16
Mailing ListThird Party Advisory
security.netapp.com / advisory/ntap-20211008-0001
Third Party Advisory