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Debian LinuxOperating system · Debian

CVE-2016-9775

HIGH · 7.8 CVSS v3.0 Published 2017-03-23
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The postrm script in the tomcat6 package before 6.0.45+dfsg-1~deb7u3 on Debian wheezy, before 6.0.45+dfsg-1~deb8u1 on Debian jessie, before 6.0.35-1ubuntu3.9 on Ubuntu 12.04 LTS and on Ubuntu 14.04 LTS; the tomcat7 package before 7.0.28-4+deb7u7 on Debian wheezy, before 7.0.56-3+deb8u6 on Debian jessie, before 7.0.52-1ubuntu0.8 on Ubuntu 14.04 LTS, and on Ubuntu 12.04 LTS, 16.04 LTS, and 16.10; and the tomcat8 package before 8.0.14-1+deb8u5 on Debian jessie, before 8.0.32-1ubuntu1.3 on Ubuntu 16.04 LTS, before 8.0.37-1ubuntu0.1 on Ubuntu 16.10, and before 8.0.38-2ubuntu1 on Ubuntu 17.04 might allow local users with access to the tomcat account to gain root privileges via a setgid program in the Catalina directory, as demonstrated by /etc/tomcat8/Catalina/attack.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The postrm (post-removal) script in Tomcat6/7/8 packages has a vulnerability where it fails to properly secure or removes setgid permissions on the Catalina directory during package removal/upgrade. A local attacker with access to the tomcat user account can place a malicious setgid program in /etc/tomcat*/Catalina/ to execute with group privileges and potentially gain root access.

MitigationUpdate the affected Tomcat packages to the patched versions (tomcat6 6.0.45+dfsg-1~deb7u3/1~deb8u1, tomcat7 7.0.28-4+deb7u7/7.0.56-3+deb8u6/7.0.52-1ubuntu0.8, tomcat8 8.0.14-1+deb8u5/8.0.32-1ubuntu1.3/8.0.37-1ubuntu0.1/8.0.38-2ubuntu1 or later). Audit /etc/tomcat*/Catalina/ directories for suspicious files.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Debian LinuxOperating system
Affected:= 7.0= 8.0
Ubuntu LinuxOperating system
Affected:= 12.04= 14.04= 16.04= 16.10
TomcatWeb server / proxy
Affected:= 6.0= 7.0= 8.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Tomcat packages
    Run 'dpkg -l | grep tomcat' (Debian/Ubuntu) or 'rpm -qa | grep tomcat' (RPM-based) to list installed Tomcat packages
    Affected if Any tomcat6, tomcat7, or tomcat8 package is installed with a version matching the affected ranges (6.0.x, 7.0.x, 8.0.x)
  2. Check installed Tomcat version
    Run 'dpkg -l tomcat6 tomcat7 tomcat8' or 'rpm -q tomcat6 tomcat7 tomcat8' to get exact version numbers. Compare against the fixed versions: tomcat6 6.0.45+dfsg-1~deb7u3/1~deb8u1 or later, tomcat7 7.0.28-4+deb7u7/7.0.56-3+deb8u6/7.0.52-1ubuntu0.8 or later, tomcat8 8.0.14-1+deb8u5/8.0.32-1ubuntu1.3/8.0.37-1ubuntu0.1/8.0.38-2ubuntu1 or later
    Affected if Installed version is lower than the fixed versions listed above
  3. Verify setgid permissions on Catalina directories
    Run 'ls -la /etc/tomcat*/Catalina/' or 'find /etc/tomcat* -name Catalina -type d -perm -g+s' to check if the Catalina directories have the setgid bit set
    Affected if The /etc/tomcat*/Catalina/ directories retain setgid permissions after package removal or upgrade operations
  4. Inspect Catalina directories for suspicious files
    Run 'ls -la /etc/tomcat*/Catalina/' to list all files in these directories and check for unexpected or recently modified executables, scripts, or binary files
    Affected if There are unexpected executable files or scripts in /etc/tomcat*/Catalina/ that were not part of the standard installation

A system is affected if Tomcat 6.0.x, 7.0.x, or 8.0.x is installed at a version below the fixed releases AND the /etc/tomcat*/Catalina/ directories have setgid permissions or contain unexpected executable files.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update the affected Tomcat packages to the patched versions (tomcat6 6.0.45+dfsg-1~deb7u3/1~deb8u1, tomcat7 7.0.28-4+deb7u7/7.0.56-3+deb8u6/7.0.52-1ubuntu0.8, tomcat8 8.0.14-1+deb8u5/8.0.32-1ubuntu1.3/8.0.37-1ubuntu0.1/8.0.38-2ubuntu1 or later). Audit /etc/tomcat*/Catalina/ directories for suspicious files.

Fix this in Debian Linux Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-9775 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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