CVE-2017-6657: Cisco Sourcefire Snort 3.0 before build 233 mishandles Ether Type Validation

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HIGH 7.5REMOTEMITIGATE

CVE-2017-6657 is a high-severity flaw (CVSS 7.5) affecting snort\+\+. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cisco Sourcefire Snort 3.0 before build 233 mishandles Ether Type Validation. Since valid ether type and IP protocol numbers do not overlap, Snort++ stores all protocol decoders in a single array. That makes it possible to craft packets that have IP protocol numbers in the ether type field which will confuse the Snort++ decoder. For example, an eth:llc:snap:icmp6 packet will cause a crash because there is no ip6 header with which to calculate the

Why this priority

High severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.1% (top 35%)
CISA exploited list	No
Published	2017-05-16
Last modified	2026-06-17

Publisher (CNA): Cisco Systems, Inc. · Vendor: cisco

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2017-05-16 17:29 UTCPublished CVE record published
2026-06-17 01:22 UTCUpdated Record last modified

cisco snort\+\+ MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy snort++ || rpm -q snort++ || snort++ --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2017-6657?

snort\+\+: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-6657 being exploited?

CVE-2017-6657 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2017-6657 affect?

CVE-2017-6657 affects snort\+\+. Severity is high (CVSS 7.5). Cisco Sourcefire Snort 3.0 before build 233 mishandles Ether Type Validation. Since valid ether type and IP protocol numbers do not overlap, Snort++ stores all protocol decoders in a single array. That makes it possible to craft packets tha

How urgent is CVE-2017-6657?

Priority 47/100. High severity; Remotely exploitable, no login, no user action

Software pages

Cisco vulnerabilities · Suricata and Snort vulnerabilities

References

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