CVE-2020-15164: in Scratch Login (MediaWiki extension) before version 1.1, any account can be logged into by using the same us

Q: How do I fix CVE-2020-15164?

scratch login: upgrade to 1.1. Exact commands for each OS are on this page.

Q: Is CVE-2020-15164 being exploited?

CVE-2020-15164 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-15164 affect?

CVE-2020-15164 affects scratch login. Severity is critical (CVSS 10.0). in Scratch Login (MediaWiki extension) before version 1.1, any account can be logged into by using the same username with leading, trailing, or repeated underscore(s), since those are treated as whitespace and trimmed by MediaWiki. This aff

Q: How urgent is CVE-2020-15164?

Priority 57/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 10.0REMOTEUPGRADE

CVE-2020-15164 is a critical-severity flaw (CVSS 10.0) affecting scratch login. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

in Scratch Login (MediaWiki extension) before version 1.1, any account can be logged into by using the same username with leading, trailing, or repeated underscore(s), since those are treated as whitespace and trimmed by MediaWiki. This affects all users on any wiki using this extension. Since version 1.1, comments by users whose usernames would be trimmed on MediaWiki are ignored when searching for the verification code.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	10.0 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.2% (top 33%)
CISA exploited list	No
Weakness	CWE-287, CWE-74
Published	2020-08-28
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: scratch-wiki

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-08-28 17:15 UTCPublished CVE record published
2026-06-17 02:56 UTCUpdated Record last modified

scratch-wiki scratch login UPGRADE

Affected: < 1.1

Fixed in: 1.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy scratch-login || rpm -q scratch-login || scratch-login --version

2. UPGRADE to 1.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade scratch-login

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade scratch-login

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-15164?

scratch login: upgrade to 1.1. Exact commands for each OS are on this page.

Is CVE-2020-15164 being exploited?

CVE-2020-15164 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-15164 affect?

CVE-2020-15164 affects scratch login. Severity is critical (CVSS 10.0). in Scratch Login (MediaWiki extension) before version 1.1, any account can be logged into by using the same username with leading, trailing, or repeated underscore(s), since those are treated as whitespace and trimmed by MediaWiki. This aff

How urgent is CVE-2020-15164?

Priority 57/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2022-42985 MEDIUM 4.8 UPGRADE The ScratchLogin extension through 1.1 for MediaWiki does not escape verification failure messages, which allo

References

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