How severe is CVE-2000-0550?

CVE-2000-0550 has a CVSS 2.0 base score of 5.0, rated medium severity.

Is CVE-2000-0550 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2000-0550?

CVE-2000-0550 primarily affects Cygnus Cygnus Network Security. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2000-0550?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2000-0550 published?

CVE-2000-0550 was published on 2000-06-09 and last updated on 2026-06-16.

CVE-2000-0550

CVE-2000-0550 is a medium-severity vulnerability in Cygnus Cygnus Network Security with a CVSS 2.0 base score of 5.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 2.0 base score 5.0)
EPSS exploit prediction: 2% (82nd percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Cygnus Cygnus Network Security
Published: 2000-06-09
Last modified: 2026-06-16

Description

Kerberos 4 KDC program improperly frees memory twice (aka "double-free"), which allows remote attackers to cause a denial of service.

Frequently asked questions

What is CVE-2000-0550?: Kerberos 4 KDC program improperly frees memory twice (aka "double-free"), which allows remote attackers to cause a denial of service.
How severe is CVE-2000-0550?: CVE-2000-0550 has a CVSS 2.0 base score of 5.0, rated medium severity.
Is CVE-2000-0550 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2000-0550?: CVE-2000-0550 primarily affects Cygnus Cygnus Network Security. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2000-0550?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2000-0550 published?: CVE-2000-0550 was published on 2000-06-09 and last updated on 2026-06-16.

References

Affected products (6)

cpe:2.3:a:cygnus:cygnus_network_security:4.0:*:*:*:*:*:*:*
cpe:2.3:a:cygnus:kerbnet:5.0:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos:4.0:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos_5:1.0:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos_5:1.1:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos_5:1.1.1:*:*:*:*:*:*:*

More vulnerabilities in Cygnus Cygnus Network Security

CVE-2000-0391 — Critical (CVSS 10.0): Buffer overflow in krshd in Kerberos 5 allows remote attackers to gain root privileges.
CVE-2000-0390 — Critical (CVSS 10.0): Buffer overflow in krb425_conv_principal function in Kerberos 5 allows remote attackers to gain root privileges.
CVE-2000-0389 — Critical (CVSS 10.0): Buffer overflow in krb_rd_req function in Kerberos 4 and 5 allows remote attackers to gain root privileges.
CVE-2000-0392 — High (CVSS 7.2): Buffer overflow in ksu in Kerberos 5 allows local users to gain root privileges.
CVE-2000-0549 — Medium (CVSS 5.0): Kerberos 4 KDC program does not properly check for null termination of AUTH_MSG_KDC_REQUEST requests, which allows…

All CVEs affecting Cygnus Cygnus Network Security →