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FedoraOperating system · Fedoraproject

CVE-2017-9109

CRITICAL · 9.8 CVSS v3.1 Published 2020-06-18
Fix available
A fix is available. Upgrade to 1.5.2 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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
An issue was discovered in adns before 1.5.2. It fails to ignore apparent answers before the first RR that was found the first time. when this is fixed, the second answer scan finds the same RRs at the first. Otherwise, adns can be confused by interleaving answers for the CNAME target, with the CNAME itself. In that case the answer data structure (on the heap) can be overrun. With this fixed, it prefers to look only at the answer RRs which come after the CNAME, which is at least arguably correct.

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

Heap buffer overflow vulnerability in adns DNS client library (versions before 1.5.2). The library fails to properly ignore answers appearing before the first resource record found during initial scanning, allowing interleaved CNAME answers to corrupt heap-allocated answer data structures.

MitigationUpgrade adns to version 1.5.2 or later, which properly validates and bounds answer resource records to only those appearing after the CNAME.

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
FedoraOperating system
Affected:= 31= 32
AdnsApplication
Affected:< 1.5.2
LeapOperating system
Affected:= 15.1

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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. Verify adns library is installed
    Check for adns packages using your package manager. On RPM systems: rpm -qa | grep -i adns. On Debian: dpkg -l | grep -i adns. Also check for linked libraries: ldd /path/to/your/application | grep adns
    Affected if adns library is present on the system
  2. Determine installed adns version
    Run: rpm -q adns or dpkg -s adns, or check the library file directly: rpm -ql adns | grep so, then read the version from the package name or use adnsresfilter --version if available
    Affected if Version is less than 1.5.2, or the package is from Fedora 31/32 or OpenSUSE Leap 15.1 without a fixed version
  3. Identify applications using adns
    Search for binaries or services linked to adns: grep -r "libadns" /proc/*/maps 2>/dev/null, or scan running processes and check their library dependencies with ldd on their executables
    Affected if Any application that performs DNS lookups is linked against the adns library
  4. Check if DNS queries can receive CNAME responses
    Review application configuration or network environment. CNAME records are most likely when DNS involves aliases (multiple hostnames pointing to the same IP). Monitor DNS traffic or check domain configurations for CNAME records pointing to your queried domains
    Affected if The application queries DNS names that have CNAME records in the response path, enabling the interleaved CNAME trigger condition

You are affected if adns library version is below 1.5.2 AND your applications using adns query DNS names that could receive CNAME responses.

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.

dbcve · scoped
Upgrade available Upgrade to 1.5.2 or later
Fixed in 1.5.2
Interim mitigation

Upgrade adns to version 1.5.2 or later, which properly validates and bounds answer resource records to only those appearing after the CNAME.

Recommended fix High confidence

adns 1.5.2 or later

  1. Identify the adns package installed on the system using the package manager (e.g., dnf for Fedora, zypper for openSUSE Leap)
  2. Update the package index to ensure latest packages are available
  3. Upgrade the adns package to version 1.5.2 or later
  4. Verify the installed version matches or exceeds 1.5.2 using: rpm -q adns or dpkg -l adns
  5. Restart any services that depend on adns to ensure the patched library is loaded
Caveat Upgrading the adns library may require dependent applications to be rebuilt or restarted to use the fixed library; no functional API changes expected

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Fedora Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,280
Get the upgrade done

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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-2017-9109 in production — separate from our analysis above.

No notes yet

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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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data