Anthropic’s Claude Opus 4.7 introduced a new tokenizer that increased token counts by roughly 1.0–1.35× (and higher in the wild), changing how inputs are sliced and triggering pricing and compatibility concerns. The change also creates fresh untrained “glitch” tokens and a widened attack surface for token-level filter bypasses, special-token smuggling, and classifier desyncs, with no comprehensive sweep of the new vocabulary yet. #ClaudeOpus4.7 #SolidGoldMagikarp
Keypoints
- Claude Opus 4.7’s new tokenizer altered BPE merges and increased token counts for the same inputs.
- New vocabularies produce untrained “glitch” tokens whose embeddings are effectively noise.
- Tokenization mismatches can bypass keyword filters and safety classifiers tuned to the old tokenizer.
- Special-token smuggling and classifier desynchronization are fresh attack vectors after the tokenizer change.
- No full glitch sweep for Opus 4.7 has been published, so defenders must remap tokenization and retest detection logic.
Read More: https://www.toxsec.com/p/token-level-ai-security-the-opus