CVE-2026-20027
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 · uneditedMultiple Cisco products are affected by a vulnerability in the processing of DCE/RPC requests that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to leak sensitive information or to restart, resulting in an interruption of packet inspection. This vulnerability is due to an error in buffer handling logic when processing DCE/RPC requests, which can result in a buffer out-of-bounds read. An attacker could exploit this vulnerability by sending a large number of DCE/RPC requests through an established connection that is inspected by Snort 3. A successful exploit could allow the attacker to obtain sensitive information in the Snort 3 data stream.
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 confidenceThis is a buffer out-of-bounds read vulnerability in Snort 3's DCE/RPC protocol handler. The vulnerability stems from improper buffer handling logic when processing DCE/RPC requests, allowing an unauthenticated remote attacker to leak sensitive information from the inspection data stream or cause Snort 3 to restart, interrupting packet inspection.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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 checksWork through these to decide whether this CVE applies to you.
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Identify Snort 3 installationRun 'snort3 -V' or 'snort -V' to display the installed Snort version. On Linux systems, also check for snort3 binary in /usr/sbin/ or /usr/local/sbin/.Affected if The output shows a Snort 3.x version (the version string will contain '3' as the major version number)
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Confirm Snort 3 version numberCompare the installed version against the affected version range for CVE-2026-20027. If the specific vulnerable versions are known, check if your installed version falls within that range.Affected if The installed Snort 3 version matches or falls within the vulnerable version range for this CVE
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Verify DCE/RPC preprocessor is enabledExamine the Snort configuration file (typically snort.conf or snort.lua) for lines containing 'dce_rpc' or 'DCE/RPC'. Also check for 'preprocessor dcerpc2' or similar DCE/RPC-related preprocessor directives.Affected if A DCE/RPC preprocessor or inspection module is explicitly enabled in the Snort configuration file
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Check for DCE/RPC traffic processingReview the snort configuration for any enabled DCE/RPC rules or inspection policies. Look for 'dce_' rule keywords or service-specific configurations for DCE/RPC traffic handling.Affected if DCE/RPC traffic inspection rules or policies are loaded and active in the Snort configuration
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Monitor for Snort restarts or crashesCheck system logs (journalctl, /var/log/messages, or /var/log/snort/) for unexpected Snort process restarts, segfaults, or crash dumps that may correlate with DCE/RPC traffic processing.Affected if Snort 3 is restarting unexpectedly or producing crash logs, especially when processing DCE/RPC traffic on the monitored network
A user is affected if they have Snort 3 installed with a version within the vulnerable range AND have DCE/RPC preprocessor/inspection enabled in their configuration, as this combination allows the buffer out-of-bounds read to trigger during DCE/RPC traffic analysis.
Generated from the published advisory. Verify against your own configuration.
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 dataApply Cisco vendor patches for affected products running Snort 3. If immediate patching is not feasible, consider filtering or blocking DCE/RPC traffic at network boundaries if not required for business operations.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-20027 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-20027 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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