Quick answers
- Is CVE-2026-51221 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-51221 being exploited in the wild.
- How severe is CVE-2026-51221?
- Informational severity, with a CVSS score of 7.5, published 29 June 2026.
- Which products and versions are affected?
- EIPStackGroup OpENer commit 76b95cf951a18d0e8481833168ab8c6943ce7c96.
- Is there a fix for CVE-2026-51221?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-51221 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-51221?
- Check whether you run EIPStackGroup OpENer at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A buffer overflow exists in the Get_Attribute_List function within EIPStackGroup OpENer (specifically commit 76b95cf). The vulnerability is triggered when the stack processes a malformed Common Packet Format (CPF) packet with an inconsistent item count. During response re-assembly in EncodeMessageRouterResponseData, the software fails to validate destination capacity before copying an oversized Message Router response into the ENIPMessage buffer. This results in an out-of-bounds write that corrupts the adjacent current_message_position pointer, leading to a segmentation fault and denial of service when the corrupted pointer is later dereferenced in AddIntToMessage. The attack is reachable over the network without authentication.
Affected products
- EIPStackGroup OpENer commit 76b95cf951a18d0e8481833168ab8c6943ce7c96
Timeline
- 2026-06-29: disclosed: Vulnerability reported via GitHub issues and published to NVD.