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Bc JavaApplication · Bouncycastle

CVE-2016-2427

MEDIUM · 5.5 CVSS v3.0 Published 2016-04-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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 AES-GCM specification in RFC 5084, as used in Android 5.x and 6.x, recommends 12 octets for the aes-ICVlen parameter field, which might make it easier for attackers to defeat a cryptographic protection mechanism and discover an authentication key via a crafted application, aka internal bug 26234568. NOTE: The vendor disputes the existence of this potential issue in Android, stating "This CVE was raised in error: it referred to the authentication tag size in GCM, whose default according to ASN.1 encoding (12 bytes) can lead to vulnerabilities. After careful consideration, it was decided that the insecure default value of 12 bytes was a default only for the encoding and not default anywhere else in Android, and hence no vulnerability existed.

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 · moderate confidence

This CVE claims that Android 5.x and 6.x used an insecure default authentication tag size (12 bytes) for AES-GCM as specified in RFC 5084, potentially making cryptographic protection weaker. However, the vendor (Google) explicitly disputes this CVE, stating it was raised in error and that the 12-byte default only applies to ASN.1 encoding, not to Android's actual implementation anywhere.

MitigationNo remediation required per Google's statement - the vendor asserts no vulnerability exists. If the CVE's logic were followed, ensuring GCM authentication tags use the full 128 bits (16 bytes) rather than 96 bits (12 bytes) would strengthen the cryptographic protection.

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
Bc JavaApplication
Affected:= 1.54
AndroidOperating system
Affected:= 5.0= 5.0.1= 5.1= 5.1.0= 6.0= 6.0.1

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

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

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 Bouncycastle Bc Java version
    Locate the bouncycastle JAR file in your application classpath or dependency list and determine the exact version number (for example, check the manifest file inside the JAR or examine your dependency management system)
    Affected if The installed version is exactly 1.54
  2. Identify Android OS version
    On the Android device, go to Settings > About Phone > Android version, or use 'adb shell getprop ro.build.version.release'
    Affected if The Android version is 5.0, 5.0.1, 5.1, 5.1.0, 6.0, or 6.0.1
  3. Check AES-GCM cipher configuration
    Inspect your cryptographic configuration or code that initializes AES-GCM ciphers (for example, Cipher.getInstance('AES/GCM/NoPadding') or equivalent) and examine the GCMParameterSpec or authentication tag length parameter
    Affected if The authentication tag is explicitly set to 12 bytes (96 bits) or uses a default that results in 12-byte tags rather than the full 16 bytes (128 bits)
  4. Verify if ASN.1 encoding is in use
    Examine whether your application uses AES-GCM with ASN.1 encoded parameters, as the CVE specifically targets the 12-byte default in ASN.1 contexts per RFC 5084
    Affected if AES-GCM is being used with ASN.1 encoding and the tag length defaults to 12 bytes

You are affected only if you use Bouncycastle 1.54, or run Android 5.x/6.x, AND actively use AES-GCM with 12-byte authentication tags in an ASN.1 context - however, Google disputes this CVE as invalid for Android, noting the 12-byte default does not apply to actual implementation.

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

No remediation required per Google's statement - the vendor asserts no vulnerability exists. If the CVE's logic were followed, ensuring GCM authentication tags use the full 128 bits (16 bytes) rather than 96 bits (12 bytes) would strengthen the cryptographic protection.

Fix this in Bc Java Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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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-2016-2427 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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