Trojan Horse: Automated Repository Poisoning against Coding Agents
A new automated attack poisoned coding-agent repositories with a 60%+ success rate and over 90% backdoor injection, beating…
Researchers introduce TrojanForge, described as the first automated framework for repository-level poisoning of coding agents, which uses AST analysis and adversarial refinement to hide malicious payloads. Tested against 384 poisoned repositories (TrojanBench) across 4 harnesses and 12 models, including commercial agents, the attack achieved over 60% poisoning success and over 90% backdoor injection, with even commercial agents failing to defend against it.
Why it matters
This is a research demonstration that autonomous coding agents operating over real repositories can be systematically manipulated into injecting backdoors via disguised, repo-native payloads rather than obvious malicious code, and that current commercial agent defenses did not catch this in the tested setup. It points to a class of supply-chain risk specific to agentic coding workflows that did not have an automated, scalable attack framework before.
What is verified
TrojanForge is presented as the first automated framework for repository-level poisoning against coding agents, using AST parsing and agent execution trace mapping to select inconspicuous payload locations. [1]
The researchers built TrojanBench, a benchmark of 384 poisoned repositories spanning 6 domains and 9 programming languages. [1]
Experiments report a stable poisoning success rate of over 60% with backdoor injection exceeding 90%. [1]
Evaluation across 4 agent harnesses and 12 models found that commercial coding agents failed to defend against repository-level poisoning. [1]
What is not
- No independent verification or replication of the reported success rates; this is a single arXiv preprint.
- The specific commercial agents and models tested are not named in the supplied abstract.
- No information on whether the paper discloses defenses, mitigations, or whether vendors were notified prior to publication.
- Unclear whether the poisoning technique requires an attacker to already have some level of repository write access or supply-chain foothold.
Sources
- 1arXiv cs.LGarxiv.org · Primary source
Original source published 16 October 2026 at 10:19.
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