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CVE-2020-10595

pam-krb5 before 4.9 has a buffer overflow that might cause remote code execution in situations...

9.8 CriticalFix available

pam-krb5 before 4.9 has a buffer overflow that might cause remote code execution in situations involving supplemental prompting by a Kerberos library. It may overflow a buffer provided by the underlying Kerberos library by a single '\0' byte if an attacker responds to a prompt with an answer of a carefully chosen length. The effect may range from heap corruption to stack corruption depending on the structure of the underlying Kerberos library, with unknown effects but possibly including code execution. This code path is not used for normal authentication, but only when the Kerberos library does supplemental prompting, such as with PKINIT or when using the non-standard no_prompt PAM configuration option.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

4.78%Up 1.6 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 9.8

pam-krb5 before 4.9 has a buffer overflow that might cause remote code execution in situations involving supplemental prompting by a Kerberos library. It may overflow a buffer provided by the underlying Kerberos library by a single '\0' byte if an attacker responds to a prompt with an answer of a carefully chosen length. The effect may range from heap corruption to stack corruption depending on the structure of the underlying Kerberos library, with unknown effects but possibly including code execution. This code path is not used for normal authentication, but only when the Kerberos library does supplemental prompting, such as with PKINIT or when using the non-standard no_prompt PAM configuration option.

Record
CVE-2020-10595
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0
7.5 HighAV:N/AC:L/Au:N/C:P/I:P/A:P
Weakness
CWE-120
Updated
2026-11-02
CVE List No score

pam-krb5 before 4.9 has a buffer overflow that might cause remote code execution in situations involving supplemental prompting by a Kerberos library. It may overflow a buffer provided by the underlying Kerberos library by a single '\0' byte if an attacker responds to a prompt with an answer of a carefully chosen length. The effect may range from heap corruption to stack corruption depending on the structure of the underlying Kerberos library, with unknown effects but possibly including code execution. This code path is not used for normal authentication, but only when the Kerberos library does supplemental prompting, such as with PKINIT or when using the non-standard no_prompt PAM configuration option.

Record
CVE-2020-10595
Updated
2026-11-02
EUVDEUVD-2020-3044 No score

pam-krb5 before 4.9 has a buffer overflow that might cause remote code execution in situations involving supplemental prompting by a Kerberos library. It may overflow a buffer provided by the underlying Kerberos library by a single '\0' byte if an attacker responds to a prompt with an answer of a carefully chosen length. The effect may range from heap corruption to stack corruption depending on the structure of the underlying Kerberos library, with unknown effects but possibly including code execution. This code path is not used for normal authentication, but only when the Kerberos library does supplemental prompting, such as with PKINIT or when using the non-standard no_prompt PAM configuration option.

Record
EUVD-2020-3044
Updated
2026-11-03
GitHub AdvisoriesGHSA-63wp-w3mg-whpq No score

pam-krb5 before 4.9 has a buffer overflow that might cause remote code execution in situations...

pam-krb5 before 4.9 has a buffer overflow that might cause remote code execution in situations involving supplemental prompting by a Kerberos library. It may overflow a buffer provided by the underlying Kerberos library by a single '\0' byte if an attacker responds to a prompt with an answer of a carefully chosen length. The effect may range from heap corruption to stack corruption depending on the structure of the underlying Kerberos library, with unknown effects but possibly including code execution. This code path is not used for normal authentication, but only when the Kerberos library does supplemental prompting, such as with PKINIT or when using the non-standard no_prompt PAM configuration option.

Record
GHSA-63wp-w3mg-whpq
Updated
2026-11-02
OSV 9.8

pam-krb5 before 4.9 has a buffer overflow that might cause remote code execution in situations involving supplemental prompting by a Kerberos library. It may overflow a buffer provided by the underlying Kerberos library by a single '\0' byte if an attacker responds to a prompt with an answer of a carefully chosen length. The effect may range from heap corruption to stack corruption depending on the structure of the underlying Kerberos library, with unknown effects but possibly including code execution. This code path is not used for normal authentication, but only when the Kerberos library does supplemental prompting, such as with PKINIT or when using the non-standard no_prompt PAM configuration option.

Record
CVE-2020-10595
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2020-10595 9.8

pam-krb5 before 4.9 has a buffer overflow that might cause remote code execution in situations involving supplemental prompting by a Kerberos library. It may overflow a buffer provided by the underlying Kerberos library by a single '\0' byte if an attacker responds to a prompt with an answer of a carefully chosen length. The effect may range from heap corruption to stack corruption depending on the structure of the underlying Kerberos library, with unknown effects but possibly including code execution. This code path is not used for normal authentication, but only when the Kerberos library does supplemental prompting, such as with PKINIT or when using the non-standard no_prompt PAM configuration option.

Record
DEBIAN-CVE-2020-10595
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2020-10595 9.8

pam-krb5 before 4.9 has a buffer overflow that might cause remote code execution in situations involving supplemental prompting by a Kerberos library. It may overflow a buffer provided by the underlying Kerberos library by a single '\0' byte if an attacker responds to a prompt with an answer of a carefully chosen length. The effect may range from heap corruption to stack corruption depending on the structure of the underlying Kerberos library, with unknown effects but possibly including code execution. This code path is not used for normal authentication, but only when the Kerberos library does supplemental prompting, such as with PKINIT or when using the non-standard no_prompt PAM configuration option.

Record
UBUNTU-CVE-2020-10595
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUSN-4314-1 No score

libpam-krb5 vulnerability

Russ Allbery discovered that pam-krb5 incorrectly handled some responses. An attacker could possibly use this issue to execute arbitrary code.

Record
USN-4314-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
libpam-krb5
Debian:12
before 4.9-1
4.9-1
libpam-krb5
Debian:13
before 4.9-1
4.9-1
libpam-krb5
Debian:14
before 4.9-1
4.9-1
libpam-krb5
Debian:8
before 4.6-3+deb8u1, plus listed versions
4.6-3
4.6-3+deb8u1
libpam-krb5
Debian:9
before 4.7-4+deb9u1, plus listed versions
4.7-4
4.7-4+deb9u1
libpam-krb5
Debian:10
before 4.8-2+deb10u1, plus listed versions
4.8-2
4.8-2+deb10u1
libpam-krb5
Ubuntu:Pro:14.04:LTS
before 4.6-2ubuntu0.1~esm1, plus listed versions
4.6-2
4.6-2ubuntu0.1~esm1
libpam-krb5
Ubuntu:16.04:LTS
before 4.7-2ubuntu0.1, plus listed versions
4.7-2
4.7-2ubuntu0.1
libpam-krb5
Ubuntu:18.04:LTS
before 4.8-1ubuntu0.1, plus listed versions
4.7-44.8-1
4.8-1ubuntu0.1

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-10595 is a critical vulnerability (CVSS 9.8) in Pam-krb5 Project Pam-krb5, published March 31, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 4.78%, the 91st percentile. Fixed in libpam-krb5 4.9-1.

References

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