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CVE

CVE-2021-3426

There's a flaw in Python 3's pydoc. A local or adjacent attacker who discovers or is able to convince another local or a

There's a flaw in Python 3's pydoc. A local or adjacent attacker who discovers or is able to convince another local or adjacent user to start a pydoc server could access the server and use it to disclose sensitive information belonging to the other user that they would not normally be able to access. The highest risk of this flaw is to data confidentiality.

This flaw affects Python versions before 3.8.9, Python versions before 3.9.3 and Python versions before 3.10.0a7.

MEDIUM · CVSS 5.7 EPSS 0.00081
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules8 YARA rules0

Affected Products & Versions

15
python< 2.7.18
python>= 3.6.0 and < 3.6.13
python>= 3.7.0 and < 3.7.10
python>= 3.8.0 and < 3.8.8
python>= 3.9.0 and < 3.9.3
pythonall versions
debian linuxall versions

Sigma Hunt Rules

8
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighPython Reverse Shell Execution Via PTY And Socket Modules
producthighInline Python Execution - Spawn Shell Via OS System Library
producthighPython One-Liners with Base64 Decoding - Linux
producthighPython Function Execution Security Warning Disabled In Excel
producthighPython One-Liners with Base64 Decoding
producthighPython Spawning Pretty TTY on Windows

Scoring & Timeline

5.7
MEDIUM · CVSS v3.1 · secalert@redhat.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD20 May 2021 · 01:15 PM
CVSS VectorCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.

Vendor Advisories

26
suse-csafopenSUSE-SU-2025:15713-1
suse-csafopenSUSE-SU-2024:14434-1
suse-csafopenSUSE-SU-2024:14109-1
suse-csafopenSUSE-SU-2024:11283-1
🔗

References & Sources

15
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://bugzilla.redhat.com/show_bug.cgi?id=1935913Issue TrackingPatchThird Party Advisory
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