What is CVE-2010-4020?

CVE-2010-4020 is a medium-severity vulnerability in Mit Kerberos 5, classified under Cryptographic Issues. CVSS score: 6.3/10. Published 2010-12-02.

How severe is CVE-2010-4020?

Medium severity. CVSS v3 base score is 6.3 out of 10.

Is CVE-2010-4020 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Mit Kerberos 5

CVE-2010-4020

MIT Kerberos 5 (aka krb5) 1.8.x through 1.8.3 does not reject RC4 key-derivation checksums, which might allow remote authenticated users to forge a (1) AD-SIGNEDPATH or (2) AD-KDC-ISSUED signature, and possibly gain privileges, by leveraging the small key space that results from certain one-byte stream-cipher operations.

Vulnerability class: POODLE (CVE-2014-3566)

Published 2010-12-02 · last modified 2026-06-16.

CVSS v3 metric

CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.019 (79.1th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 79th percentile — 79.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.019 · newest: 0.019 · change: 0.000

Affected products

Mit Kerberos 5 — versions 1.8.1, 1.8.2, 1.8.3

Weakness classification (CWE)

CWE-310 — Cryptographic Issues

Public proof-of-concept exploits

References

www.vupen.com/english/advisories/2010/3094 (vdb-entry)
www.oracle.com/technetwork/topics/security/cpujul2015-2367936.html (Patch, Vendor Advisory)
www.mandriva.com/security/advisories (vendor-advisory)
lists.fedoraproject.org/pipermail/package-announce/2010-December/051999.html (vendor-advisory)
kb.vmware.com/kb/1035108
www.vupen.com/english/advisories/2010/3118 (vdb-entry)
www.securityfocus.com/archive/1/514953/100/0/threaded (mailing-list)
lists.opensuse.org/opensuse-security-announce/2010-12/msg00000.html (vendor-advisory)
www.vmware.com/security/advisories/VMSA-2011-0007.html
lists.apple.com/archives/security-announce/2011/Mar/msg00006.html (vendor-advisory)

Frequently asked questions

What is CVE-2010-4020?: CVE-2010-4020 is a medium-severity vulnerability in Mit Kerberos 5, classified under Cryptographic Issues. CVSS score: 6.3/10. Published 2010-12-02.
How severe is CVE-2010-4020?: Medium severity. CVSS v3 base score is 6.3 out of 10.
Is CVE-2010-4020 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.