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GitHub Agentic Workflows indirect prompt injection security flaw

Vulnerability
First reported
Last updated
Happening score
H score 27
1 unique sources, 1 articles

Summary

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GitHub Agentic Workflows has an indirect prompt injection flaw that can let a public issue leak content from private repositories into public comments. The risk is highest when an organization gives the agent broad read access across repos, because attacker-controlled text can steer the agent into exfiltrating data it can already read. In Noma Security's proof of concept, the workflow pulled a private repository's README and posted it publicly, and a one-word change, Additionally, bypassed GitHub's guardrail.

Related Happenings

Ghostcommit PNG-embedded prompt injection against AI code reviewers

Technical Analysis
H score25 First: 11.07.2026 12:03 Last: 11.07.2026 12:03 Sources 1

About this happening: Researchers demonstrated Ghostcommit, a PNG-embedded prompt-injection technique that can bypass AI code review and leak .env secrets into committed source. The pay...

Open Happening

Single organization's private GitHub repository cloned after confirmed access

Data Leak
H score12 First: 09.07.2026 21:38 Last: 09.07.2026 21:38 Sources 1

About this happening: Confirmed access to a private GitHub repository belonging to one organization marks a concrete data exposure and raises the risk of source-code or internal-content...

Open Happening

GitHub API enumeration campaign targeting corporate organizations

Campaign
H score17 First: 09.07.2026 21:38 Last: 09.07.2026 21:38 Sources 1

About this happening: A GitHub API reconnaissance campaign is systematically mapping corporate organizations, repositories, and user accounts across multiple companies, expanding the risk of fo...

Open Happening

GitHub npm GAT publish-token mitigation guidance

Advisory/Mitigation
H score25 First: 09.07.2026 19:49 Last: 09.07.2026 19:49 Sources 1

About this happening: GitHub is steering npm users away from long-lived publish tokens as npm GATs that bypass 2FA lose direct publishing and sensitive-management abilities. The recomme...

Open Happening

GitHub actions/checkout blocks fork pull request checkouts by default in privileged workflows

Security Tool/Service
H score11 First: 23.06.2026 17:22 Last: 23.06.2026 17:22 Sources 1

About this happening: GitHub's actions/checkout now refuses common pwn request patterns by default, cutting the risk of attacker-controlled code execution in privileged GitHub Actions workf...

Open Happening

Timeline

  1. 07.07.2026 17:04 2 articles · 13d ago

    Noma Security discloses GitLost prompt injection flaw in GitHub Agentic Workflows

    Initial Disclosure

    Noma Security disclosed GitLost, an indirect prompt injection flaw in GitHub Agentic Workflows that can steer an agent with broad repository read access into copying private repository content into a public issue comment. The proof of concept showed a normal-looking public issue could exfiltrate a private repository's README, and a one-word prefix, "Additionally", was enough to bypass GitHub's guardrail.

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