CVE-2020-17477: Incorrect LDAP ACLs in ucs-school-ldap-acls-master in UCS@school before 4.4v5-errata allow remote teachers, st

Q: How do I fix CVE-2020-17477?

ucs\@school: upgrade to newer than 4.4. Exact commands for each OS are on this page.

Q: Is CVE-2020-17477 being exploited?

CVE-2020-17477 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-2020-17477 affect?

CVE-2020-17477 affects ucs\@school. Severity is medium (CVSS 6.5). Incorrect LDAP ACLs in ucs-school-ldap-acls-master in UCS@school before 4.4v5-errata allow remote teachers, staff, and school administrators to read LDAP password hashes (sambaNTPassword, krb5Key, sambaPasswordHistory, and pwhistory) via LD

Q: How urgent is CVE-2020-17477?

Priority 33/100. No elevated risk signals yet.

Routine

MEDIUM 6.5UPGRADE

CVE-2020-17477 is a medium-severity flaw (CVSS 6.5) affecting ucs\@school. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Incorrect LDAP ACLs in ucs-school-ldap-acls-master in UCS@school before 4.4v5-errata allow remote teachers, staff, and school administrators to read LDAP password hashes (sambaNTPassword, krb5Key, sambaPasswordHistory, and pwhistory) via LDAP search requests. For example, a teacher can gain administrator access via an NTLM hash.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.5% (top 61%)
CISA exploited list	No
Weakness	CWE-522
Published	2023-10-26
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: univention

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

Am I affected?

Timeline

2023-10-26 13:15 UTCPublished CVE record published
2026-06-17 02:58 UTCUpdated Record last modified

univention ucs\@school UPGRADE

Affected: <= 4.4

Fixed in: newer than 4.4

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy ucsschool || rpm -q ucsschool || ucsschool --version

2. UPGRADE to newer than 4.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade ucsschool

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ucsschool

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-2020-17477?

ucs\@school: upgrade to newer than 4.4. Exact commands for each OS are on this page.

Is CVE-2020-17477 being exploited?

CVE-2020-17477 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-2020-17477 affect?

CVE-2020-17477 affects ucs\@school. Severity is medium (CVSS 6.5). Incorrect LDAP ACLs in ucs-school-ldap-acls-master in UCS@school before 4.4v5-errata allow remote teachers, staff, and school administrators to read LDAP password hashes (sambaNTPassword, krb5Key, sambaPasswordHistory, and pwhistory) via LD

How urgent is CVE-2020-17477?

Priority 33/100. No elevated risk signals yet.

References

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