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 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.

Read the notes from the security team

Mitigation

Do not expose the pydoc webserver to untrusted users.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
python2.7	24.10 oracular	Not in release
	24.04 LTS noble	Not in release
	23.10 mantic	Not in release
	23.04 lunar	Not in release
	22.10 kinetic	Not affected
	22.04 LTS jammy	Not affected
	21.10 impish	Not affected
	21.04 hirsute	Not affected
	20.10 groovy	Not affected
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected
python3.10	24.10 oracular	Not in release
	24.04 LTS noble	Not in release
	23.10 mantic	Not in release
	23.04 lunar	Not in release
	22.10 kinetic	Not affected
	22.04 LTS jammy	Not affected
	21.10 impish	Not affected
	21.04 hirsute	Not affected
	20.10 groovy	Not in release
	20.04 LTS focal	Not in release
	18.04 LTS bionic	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
python3.4	24.10 oracular	Not in release
	24.04 LTS noble	Not in release
	23.10 mantic	Not in release
	23.04 lunar	Not in release
	22.10 kinetic	Not in release
	22.04 LTS jammy	Not in release
	21.10 impish	Not in release
	21.04 hirsute	Not in release
	20.10 groovy	Not in release
	20.04 LTS focal	Not in release
	18.04 LTS bionic	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Fixed 3.4.3-1ubuntu1~14.04.7+esm12 Ubuntu Pro
python3.5	24.10 oracular	Not in release
	24.04 LTS noble	Not in release
	23.10 mantic	Not in release
	23.04 lunar	Not in release
	22.10 kinetic	Not in release
	22.04 LTS jammy	Not in release
	21.10 impish	Not in release
	21.04 hirsute	Not in release
	20.10 groovy	Not in release
	20.04 LTS focal	Not in release
	18.04 LTS bionic	Not in release
	16.04 LTS xenial	Fixed 3.5.2-2ubuntu0~16.04.13+esm2 Ubuntu Pro
	14.04 LTS trusty	Fixed 3.5.2-2ubuntu0~16.04.4~14.04.1+esm1 Ubuntu Pro
python3.6	24.10 oracular	Not in release
	24.04 LTS noble	Not in release
	23.10 mantic	Not in release
	23.04 lunar	Not in release
	22.10 kinetic	Not in release
	22.04 LTS jammy	Not in release
	21.10 impish	Not in release
	21.04 hirsute	Not in release
	20.10 groovy	Not in release
	20.04 LTS focal	Not in release
	18.04 LTS bionic	Fixed 3.6.9-1~18.04ubuntu1.7
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
python3.7	24.10 oracular	Not in release
	24.04 LTS noble	Not in release
	23.10 mantic	Not in release
	23.04 lunar	Not in release
	22.10 kinetic	Not in release
	22.04 LTS jammy	Not in release
	21.10 impish	Not in release
	21.04 hirsute	Not in release
	20.10 groovy	Not in release
	20.04 LTS focal	Not in release
	18.04 LTS bionic	Fixed 3.7.5-2ubuntu1~18.04.2+esm1 Ubuntu Pro
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
python3.8	24.10 oracular	Not in release
	24.04 LTS noble	Not in release
	23.10 mantic	Not in release
	23.04 lunar	Not in release
	22.10 kinetic	Not in release
	22.04 LTS jammy	Not in release
	21.10 impish	Not in release
	21.04 hirsute	Not in release
	20.10 groovy	Ignored end of life
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Fixed 3.8.0-3ubuntu1~18.04.2+esm2 Ubuntu Pro
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
python3.9	24.10 oracular	Not in release
	24.04 LTS noble	Not in release
	23.10 mantic	Not in release
	23.04 lunar	Not in release
	22.10 kinetic	Not in release
	22.04 LTS jammy	Not in release
	21.10 impish	Fixed 3.9.5-2ubuntu1
	21.04 hirsute	Fixed 3.9.5-3~21.04
	20.10 groovy	Fixed 3.9.5-3~20.10.1
	20.04 LTS focal	Fixed 3.9.5-3~20.04.1
	18.04 LTS bionic	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release

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Notes

mdeslaur

getfile introduced in 3.2.0

sbeattie

upstream fixed this by removing the getfile feature

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
python3.10	Upstream: 9b99947
python3.6	Upstream: 5b1e502
python3.7	Upstream: 7c2284f
python3.8	Upstream: 7e38d33
python3.9	Upstream: ed753d9

Severity score breakdown

Parameter	Value
Base score	5.7 · Medium
Attack vector	Adjacent
Attack complexity	Low
Privileges required	Low
User interaction	None
Scope	Unchanged
Confidentiality	High
Integrity impact	None
Availability impact	None
Vector	CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

References

Related Ubuntu Security Notices (USN)

USN-5342-1
Python vulnerabilities
28 March 2022

USN-5342-3
Python vulnerability
23 May 2022

USN-6891-1
Python vulnerabilities
11 July 2024

Cvss 3 Severity Score