CVE-2017-11368: In MIT Kerberos 5 (aka krb5) 1.7 and later, an authenticated attacker can cause a KDC assertion failure by sen

This month

MEDIUM 6.5MITIGATEDOWNGRADEDOWNGRADE

CVE-2017-11368 is a medium-severity flaw (CVSS 6.5) affecting fedora, kerberos, kerberos 5. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In MIT Kerberos 5 (aka krb5) 1.7 and later, an authenticated attacker can cause a KDC assertion failure by sending invalid S4U2Self or S4U2Proxy requests.

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	2.4% (top 16%)
CISA exploited list	No
Weakness	CWE-617
Published	2017-08-09
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: fedoraproject · mit

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

Am I affected?

Timeline

2017-08-09 18:29 UTCPublished CVE record published
2026-06-17 01:01 UTCUpdated Record last modified

fedoraproject fedora MITIGATE

Affected: 25 · 26

Fixed in: no fixed release known

Safe to downgrade to: a release before 25

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

mit kerberos DOWNGRADE

Affected: 5-1.13.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 5-1.13.7

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 5-1.13.7 (Debian / Ubuntu)

apt-cache madison kerberos sudo apt install kerberos=<VERSION_BEFORE_5-1.13.7> sudo apt-mark hold kerberos

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list kerberos sudo dnf downgrade kerberos-<VERSION_BEFORE_5-1.13.7> sudo dnf versionlock add kerberos

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

mit kerberos 5 DOWNGRADE

Affected: 1.7 · 1.7.1 · 1.8 · 1.8.1 · 1.8.2 · 1.8.3 · 1.8.4 · 1.8.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.7

1. Check installed version

apt-cache policy kerberos-5 || rpm -q kerberos-5 || kerberos-5 --version

2. No fixed release: DOWNGRADE to a release before 1.7 (Debian / Ubuntu)

apt-cache madison kerberos-5 sudo apt install kerberos-5=<VERSION_BEFORE_1.7> sudo apt-mark hold kerberos-5

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list kerberos-5 sudo dnf downgrade kerberos-5-<VERSION_BEFORE_1.7> sudo dnf versionlock add kerberos-5

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2017-11368?

fedora: mitigate or apply the listed mitigation; kerberos: downgrade or apply the listed mitigation; kerberos 5: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-11368 being exploited?

CVE-2017-11368 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-2017-11368 affect?

CVE-2017-11368 affects fedora, kerberos, kerberos 5. Severity is medium (CVSS 6.5). In MIT Kerberos 5 (aka krb5) 1.7 and later, an authenticated attacker can cause a KDC assertion failure by sending invalid S4U2Self or S4U2Proxy requests.

How urgent is CVE-2017-11368?

Priority 44/100. No elevated risk signals yet.

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References

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