OpenSSH up to 6.x on Non-OpenBSD monitor.c mm_answer_pam_free_ctx MONITOR_REQ_PAM_FREE_CTX Request access control

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6.1$0-$5k0.00

Summaryinfo

A vulnerability was found in OpenSSH up to 6.x on Non-OpenBSD. It has been classified as problematic. Affected by this issue is the function mm_answer_pam_free_ctx of the file monitor.c. Performing a manipulation as part of MONITOR_REQ_PAM_FREE_CTX Request results in access control. This vulnerability is reported as CVE-2015-6564. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in OpenSSH up to 6.x on Non-OpenBSD (Connectivity Software). It has been classified as problematic. This affects the function mm_answer_pam_free_ctx of the file monitor.c. The manipulation as part of a MONITOR_REQ_PAM_FREE_CTX Request leads to a access control vulnerability. CWE is classifying the issue as CWE-264. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Use-after-free vulnerability in the mm_answer_pam_free_ctx function in monitor.c in sshd in OpenSSH before 7.0 on non-OpenBSD platforms might allow local users to gain privileges by leveraging control of the sshd uid to send an unexpectedly early MONITOR_REQ_PAM_FREE_CTX request.

The weakness was disclosed 08/24/2015 by Moritz Jodeit as confirmed mailinglist post (oss-sec). The advisory is shared at seclists.org. This vulnerability is uniquely identified as CVE-2015-6564 since 08/21/2015. An attack has to be approached locally. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1068 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 86656 (AIX OpenSSH Advisory : openssh_advisory6.asc), which helps to determine the existence of the flaw in a target environment. It is assigned to the family AIX Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 236003 (Red Hat Update for openssh (RHSA-2016:0741)).

Upgrading to version 7.0 eliminates this vulnerability. A possible mitigation has been published 3 months after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at X-Force (105882), Tenable (86656), SecurityFocus (BID 76317†) and Vulnerability Center (SBV-54664†). The entries VDB-77396, VDB-77398, VDB-78828 and VDB-80656 are pretty similar. If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.1

VulDB Base Score: 5.9
VulDB Temp Score: 5.2
VulDB Vector: 🔍
VulDB Reliability: 🔍

ADP CISA Base Score: 7.0
ADP CISA Vector: 🔍

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Access control
CWE: CWE-264
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: No

Availability: 🔍
Status: Unproven

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 86656
Nessus Name: AIX OpenSSH Advisory : openssh_advisory6.asc
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 14611
OpenVAS Name: Amazon Linux Local Check: alas-2015-625
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
Exposure Time: 🔍

Upgrade: OpenSSH 7.0
Patch: github.com

Timelineinfo

08/12/2015 🔍
08/21/2015 +9 days 🔍
08/23/2015 +2 days 🔍
08/24/2015 +1 days 🔍
08/24/2015 +0 days 🔍
09/16/2015 +23 days 🔍
10/21/2015 +35 days 🔍
10/29/2015 +8 days 🔍
11/29/2015 +31 days 🔍
05/28/2026 +3833 days 🔍

Sourcesinfo

Advisory: 5e75f5198769056089fb06c4d738ab0e5abc66f7
Researcher: Moritz Jodeit
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2015-6564 (🔍)
GCVE (CVE): GCVE-0-2015-6564
GCVE (VulDB): GCVE-100-77397

OVAL: 🔍

X-Force: 105882 - OpenSSH mm_answer_pam_free_ctx privilege escalation
SecurityFocus: 76317 - OpenSSH PAM Support Multiple Remote Code Execution Vulnerabilities
Vulnerability Center: 54664 - OpenSSH before 7.0 Local Privileges Escalation via Leverage Control of the sshd uid, Medium

See also: 🔍

Entryinfo

Created: 08/24/2015 10:17
Updated: 05/28/2026 04:08
Changes: 08/24/2015 10:17 (69), 05/09/2018 11:37 (17), 06/13/2022 08:51 (4), 06/13/2022 08:52 (1), 05/28/2026 04:08 (27)
Complete: 🔍
Cache ID: 216::103

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