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Ubuntu LinuxOperating system · Canonical

CVE-2015-8920

MEDIUM · 5.5 CVSS v3.0 Published 2016-09-20
Fix available
A fix is available. Upgrade to after 3.1.901a or later.
See remediation →
58/100
Remediation priority · Elevated
No privileges

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 _ar_read_header function in archive_read_support_format_ar.c in libarchive before 3.2.0 allows remote attackers to cause a denial of service (out-of-bounds stack read) via a crafted ar file.

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 _ar_read_header function in archive_read_support_format_ar.c in libarchive versions before 3.2.0 contains an out-of-bounds stack read vulnerability when parsing specially crafted ar (archive) files. A remote attacker can trigger this by providing a malicious ar file, causing a denial of service through the out-of-bounds read.

MitigationUpdate libarchive to version 3.2.0 or later to obtain the fix. If immediate updating is not feasible, implement strict validation of ar files before processing and consider restricting untrusted file input sources.

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
Ubuntu LinuxOperating system
Affected:= 12.04= 14.04= 15.10= 16.04
Suse Linux Enterprise Software Development KitApplication
Affected:= 12.0
Suse Linux Enterprise DesktopOperating system
Affected:= 12.0
Suse Linux Enterprise ServerOperating system
Affected:= 12.0
LibarchiveApplication
Affected:<= 3.1.901a

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
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/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 libarchive version
    Run 'dpkg -l libarchive13' on Ubuntu or 'rpm -q libarchive' on SUSE to query the installed package version. Alternatively, run 'archive --version' if the tool is available, or check the library file directly with 'strings /usr/lib/x86_64-linux-gnu/libarchive.so.* 2>/dev/null | grep -i libarchive' to find version strings.
    Affected if The version number returned is less than 3.2.0, or the package is not found (which may indicate the library is bundled elsewhere)
  2. Find binaries or applications using libarchive
    Search for executables that link to libarchive by running 'ldd $(which ar) 2>/dev/null | grep archive' or 'ldconfig -p | grep archive'. Also check 'dpkg -l | grep libarchive' on Ubuntu or 'rpm -qa | grep libarchive' on SUSE to list all installed libarchive packages.
    Affected if Any libarchive library version below 3.2.0 is found on the system
  3. Verify ar archive parsing capability is present
    Check if the libarchive ar format module exists. On systems with dynamic libraries, verify /usr/lib/x86_64-linux-gnu/libarchive.so.* (Ubuntu) or /usr/lib64/libarchive.so.* (SUSE) exists. Test ar parsing capability by running 'ar --help' or attempting to list a test ar file with 'ar -t <file>' where <file> is an ar archive.
    Affected if The ar tool or libarchive library is present and can parse ar format files
  4. Check for recent processing of untrusted ar files
    Review application logs, mail filters, or backup systems that may have processed ar archives from untrusted sources. Check /var/log for any archive-related utilities (like 'tar' which may auto-detect and process ar files) that were run recently.
    Affected if Any untrusted ar files may have been processed by libarchive-based tools since the library was installed

The system is affected if libarchive version 3.2.0 or later is not installed, AND any application or tool capable of parsing ar format files is present and has access to potentially untrusted ar input.

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
Upgrade available Upgrade to a release after 3.1.901a
Interim mitigation

Update libarchive to version 3.2.0 or later to obtain the fix. If immediate updating is not feasible, implement strict validation of ar files before processing and consider restricting untrusted file input sources.

Fix this in Ubuntu Linux Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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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-2015-8920 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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