Nikita Benkovich and Vitalii ValkovSecurity researchersagyn
Security research on agyn's own accounts. Seer with automatic coding-agent handoff. CVE-2026-90999.
agyn blog, published Read the write-up (opens agyn blog in a new tab)
Observation
agyn showed that a made-up error sent to a public DSN can steer Seer's automatic handoff into running attacker code.
- Takeaway
- For projects with a public DSN, require a person to start each coding-agent handoff. Give the agent only the repository access it needs.
- What happened
- Anyone can send an error event to a frontend project's public DSN. agyn researchers sent a fabricated report that Seer rated fixable from issue data alone. Seer handed it to a coding agent, which fetched and ran attacker-controlled code with access to connected repositories. The same manipulation worked on every leading model the researchers tried. The researchers disclosed it to Sentry, and CERT/CC tracks it as VU#212479. The post suggests pausing automatic handoff until teams have reviewed it or a fix is available.
- Public engineering write-up (agyn security research)
- No team metrics reported
Deployment details
Security research on agyn's own accounts. Seer with automatic coding-agent handoff. CVE-2026-90999.
- Public engineering write-up (agyn security research)
- No team metrics reported
- Team
- agyn security research
- Workload
- Fabricated frontend error events sent to a public DSN
- Product version
- Seer with automatic handoff to a coding agent and automated remediation on, September 2026