CVE-2026-56696: OpenHarness - Prompt Injection via /issue and /pr_comments Slash Commands

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-23 · updated 2026-10-25
Weakness: CWE-862

Description

OpenHarness /issue and /pr_comments slash commands lack remote_invocable=False protection, allowing remote channel senders to write attacker-controlled Markdown into project context files. Admitted remote attackers can inject malicious content into .openharness/issue.md and .openharness/pr_comments.md files, which are subsequently injected into runtime system prompts, persistently influencing local agent behavior.

Affected products

HKUDS OpenHarness: through 0.1.9

References

https://github.com/HKUDS/OpenHarness/commit/27bb93b810e9ea8fa4832eab7152eeb3b4a6bffb
https://github.com/HKUDS/OpenHarness/pull/272
https://www.vulncheck.com/advisories/openharness-prompt-injection-via-issue-and-pr-comments-slash-commands
https://github.com/HKUDS/OpenHarness/pull/272

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