# GLM-5.3: Z.ai's Model Tops CyberGym, Weights in Two Weeks

GLM-5.3 posts a more-than-6× Terminal-Bench 3.0 jump and leads CyberGym at 84.5%, ahead of Mythos 5 and GPT-5.6 Sol. Open weights land in two weeks, not today.

By Neomanex. Updated 2026-08-14.

GLM-5.3 is the first open-weights model to lead CyberGym — and it beats Anthropic's [Mythos 5](/models/mythos-5) and OpenAI's [GPT-5.6 Sol](/models/gpt-5-6-sol) to get there. That's the headline. The catch: the weights don't ship today — they're staged about two weeks out, gated on safety evaluation and hardening. (Every number here is Z.ai's own, run through the Claude Code harness; we haven't independently reproduced them.)

## What happened

Z.ai released GLM-5.3 as a post-training-only update on the same base model as [GLM-5.2](/models/glm-5-2). "Scaling post-training is all we did," per Z.ai. This isn't a new model — it's what a month of environment-scaled RL bought.

| Benchmark | GLM-5.2 | GLM-5.3 | Where it lands |
|---|---|---|---|
| Terminal-Bench 3.0 | 4.6% | 28.3% | Open-source SOTA |
| Agents' Last Exam | 23.8% | 28.5% | — |
| CyberGym | — | 84.5% | Ahead of Mythos 5 (83.8%), GPT-5.6 Sol (83.6%) |
| ExploitBench | 24.4% | 54.4% | Still trails [Mythos 5](/models/mythos-5) (78.0%), GPT-5.6 Sol (76.5%) |

Z.ai says the model found 2,436 vulnerabilities across 269 projects — 1,097 critical or high, some dating back to 1981.

## Why it matters

The cyber capability is the part to watch. GLM-5.3 is the first open-weights model to top CyberGym, and the more-than-doubling on ExploitBench (24.4% to 54.4%) is the biggest gain exactly where the closed frontier is furthest ahead — it still trails Mythos 5 and GPT-5.6 Sol, but it closes a lot of that gap in a single post-training run.

For the open-weight world, this sharpens the frontier on both coding and security. But "open" is a promise with a two-week fuse, not a fact today: right now the only way to reach GLM-5.3 is through the GLM Coding Plan (usable in ZCode, Claude Code, OpenCode).

## What changes for you

- **You can't run it locally yet.** Weights land on Hugging Face in about two weeks, after the safety review and hardening.
- **A breaking change ships today.** `thinking.type: "disabled"` is no longer supported — set `thinking.type` to `"enabled"` and use `reasoning_effort` (low/high/max).
- **Test it now** through the GLM Coding Plan or ZCode if you want the capability before the weights drop.

## FAQ

**Is GLM-5.3 actually open weights today?** No. The weights are staged roughly two weeks out, gated on safety evaluation and hardening. Until then it's only reachable via the GLM Coding Plan and ZCode.

**Is this a new model?** No — it's post-training on the same base as GLM-5.2. The gains come from scaling post-training alone, which is what makes the Terminal-Bench 3.0 jump from 4.6% to 28.3% notable.

**What do I change if I migrate from GLM-5.2?** Set `thinking.type` to `"enabled"` and add `reasoning_effort` (low/high/max). `thinking.type: "disabled"` no longer works.

**Bottom line:** the open-weight frontier just got sharper on both coding and security — but the actual weights are a two-week promise, not something you can download today.

Canonical: https://neomanex.com/news/glm-5-3-launch