Remote service crash via unchecked response copy
Published Jun 29, 2026 · Updated Jun 29, 2026
Buffer overflow in EIPStackGroup OpENer commit 76b95c allows remote attackers to crash the server via a crafted EtherNet/IP CPF packet. GetAttributeList accepts an excessive attacker-controlled attribute count, and EncodeMessageRouterResponseData copies the oversized response into a 512-byte ENIPMessage buffer without checking remaining capacity. Unauthenticated access to the OpENer TCP service is sufficient; the overwrite corrupts the adjacent message-position pointer, which a later write dereferences and terminates the process.
Summary
What happened
Buffer overflow in EIPStackGroup OpENer commit 76b95c allows remote attackers to crash the server via a crafted EtherNet/IP CPF packet. GetAttributeList accepts an excessive attacker-controlled attribute count, and EncodeMessageRouterResponseData copies the oversized response into a 512-byte ENIPMessage buffer without checking remaining capacity. Unauthenticated access to the OpENer TCP service is sufficient; the overwrite corrupts the adjacent message-position pointer, which a later write dereferences and terminates the process.
The record
- CVE
- CVE-2026-51221
- Published
- Jun 29, 2026
- Updated
- Jun 29, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 29, 2026CVE publishedPublication date reported by the CVE source.
- Jun 29, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
- OpENer issue 567 PoC and replay programfunctional · demonstrated
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Technologies
Your stack
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Your stack
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