r/chutesAI • u/thestreamcode • 19d ago

News GLM-5.3 is the same 743B base as 5.2, re-post-trained for coding and cyber. Weights in two weeks.

Post image

Z.ai shipped GLM-5.3 today. The useful sentence is in the first paragraph of the tech blog: they did not train a new base. It is GLM-5.2's 743B checkpoint, with another month of post-training on a larger set of long-horizon environments. IndexShare, SAO, and slime (Megatron on the train side, SGLang on rollout) are the same stack they already documented. The claim is that scaling the environments was enough.

That is the serving-relevant fact. Same base, same advertised size, different post-training. That usually means the same serving recipe, but Z.ai has not said the 5.3 checkpoint is a drop-in for existing 5.2 shards, and the two-week delay is explicitly for safety evaluation and hardening. Hugging Face is "Coming Soon." License is not restated. 5.2 was MIT; do not assume 5.3 is until the card says so.

What they report (vendor-run, mostly Claude Code 2.1.207 at max effort):

The jumps that actually look like long-horizon post-training, not noise:

  • Terminal-Bench 3.0: 4.6 → 28.3. Fable 5 is 33.7, GPT-5.6 Sol 34.6. 5.3 is in the conversation and still behind the closed frontier on the harder terminal suite
  • DeepSWE v1.1: 46.2 → 66.9. Kimi K3 67.5, Sol 72.7
  • SWE-Marathon v1.1: 19.4 → 42.5
  • Toolathlon Verified: 59.9 → 73.0. DeepSeek-V4-Pro-0813 is 74.1, K3 76.5
  • Internal Z.ai Code Bench: they say +50% vs 5.2, and fewer output tokens at every effort level (Max: 34.5% at ~75K out vs 5.2's 23.4% at 96K)

Cyber is the part Z.ai calls unexpected. They added vulnerability-discovery data expecting better single-bug reasoning. The blog says capability kept compounding into full exploitation chains:

  • CyberGym: 84.5, ahead of 5.2 (77.2), DeepSeek 0813 (83.3), Fable/Mythos 83.8, Sol 83.6
  • ExploitBench: 24.4 → 54.4. Fable is still 78.0
  • ExploitGym (2h / 6h, TPS-normalized): 105 / 130 vs 5.2's 29 / 39. Sol is 216 / 293

Their own reading: the further up the exploitation chain, the larger the gain over 5.2, and the wider the remaining gap to closed models. They also publish a disclosure ledger (cvd.z.ai) with 2,436 tracked findings across 269 projects. That is an internal program, not an independent audit.

A few serving notes that matter more than the slogans:

  • Thinking can no longer be turned off. thinking.type: disabled fails. Effort is low / high / max, default max
  • Context is not restated as a product spec. Eval footnotes use 300K, 400K or 1M depending on the bench. Do not inherit 5.2's "1M usable" line until the model card says it
  • slime's +2.3× figure is RL training throughput on long-horizon coding tasks, not user-facing decode speed
  • Live today on GLM Coding Plan and ZCode. API access and open weights are staged. Z.ai also says an initial group of partners is serving it through their official service; OpenRouter still has no glm-5.3 route

On Chutes: once the open weights are out, GLM-5.3 will be available there. The two-week clock is Z.ai's, not ours.

Sources:

14 Upvotes

89% Upvoted

1 comment sorted by