This week · model card updated October 14; model released August 25

GLM-5.3 tops just three of 16 tests; scores are Z.ai's own

Z.ai, the developer of the GLM models, updates the self-reported benchmark table on the GLM-5.3 model card: GLM-5.3 leads on only three of 16 tests, and scores 54.4 on ExploitBench, an exploit-writing test, against 78.0 for Fable 5. The three tests GLM-5.3 leads are CyberGym, AutomationBench and GDPval-AA. CyberGym is the vulnerability-discovery benchmark the model card lists: GLM-5.3 84.5, Fable 5 83.8, GPT-5.6 Sol 83.6 (GLM-5.3 model card, 2026-10-14). The model card says: "GLM-5.3 uses the same base model as GLM-5.2 — every gain comes from post-training." Each column uses a different harness, all scores are Z.ai's own, and there is no independent evaluation. Read with the archive pick: on its own scores, GLM-5.3 nearly matches closed flagships at finding vulnerabilities and still trails by a margin at writing exploits. These are one model's self-reported scores and say nothing about open-weight models as a class. How we checked →

Concept illustration: two open laptops stand side by side on a beige surface with their backs to the viewer, the left one brick-red and the right one off-white, each crossed by a black band lettered GLM-5.3 and FABLE 5 respectively. Behind them sits a person with dark wavy hair in a black turtleneck, wearing a lanyard with a small white card, in front of a large pale pink circle, and at upper left is a black rectangular sign with a red slanted-stripe mark and white lettering Z.AI.

Source and checks

This item ran in the brief of Oct 16, 2026, alongside 19 other items. How we checked it, the quote checks and what was still missing that day are on that issue's How we checked page.

Cite this item

SecondSource (2026). "GLM-5.3 tops just three of 16 tests; scores are Z.ai's own." https://secondsource.io/en/research/2026-10-16-3/. Accessed access date.