CVE-2017-18640

Publication date 12 December 2019

Last updated 25 August 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

7.5 · High

Score breakdown

Description

The Alias feature in SnakeYAML before 1.26 allows entity expansion during a load operation, a related issue to CVE-2003-1564.

Read the notes from the security team

Status

Package Ubuntu Release Status
snakeyaml 25.04 plucky
Not affected
24.10 oracular
Not affected
24.04 LTS noble
Not affected
23.10 mantic Ignored end of life, was needs-triage
23.04 lunar Ignored end of life, was needs-triage
22.10 kinetic Ignored end of life, was needs-triage
22.04 LTS jammy
Not affected
21.10 impish Ignored end of life
21.04 hirsute Ignored end of life
20.10 groovy Ignored end of life
20.04 LTS focal
Fixed 1.25+ds-2ubuntu0.1+esm1
19.10 eoan Ignored end of life
19.04 disco Ignored end of life
18.04 LTS bionic
Fixed 1.23-1+deb10u1ubuntu0.1~esm1
16.04 LTS xenial
Fixed 1.12-2ubuntu0.16.04.1~esm2
14.04 LTS trusty
Fixed 1.12-2ubuntu0.14.04.1~esm2

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Notes

alexmurray

Upstream dispute this as a valid CVE - https://bitbucket.org/asomov/snakeyaml/issues/377/allow-configuration-for-preventing-billion#comment-55227358 - and they added a test-case for this type of attack of 2 years ago https://bitbucket.org/asomov/snakeyaml/commits/04378d05777d21d114a9cdc24976ad49c8919222 so this would appear to be a non-issue

john-breton

Upstream has since released a fix for this CVE.

Patch details

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

Package Patch details
snakeyaml

Severity score breakdown

Parameter Value
Base score 7.5 · High
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact None
Availability impact High
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Related Ubuntu Security Notices (USN)

    • USN-7368-1
    • SnakeYAML vulnerability
    • 27 March 2025

Other references