Benchmark Almanac

Binary Exploitation Benchmark (Anthropic, OSS-Fuzz based)

Claude Opus 5.5 91.1% leads since Sep 2026 Only in system cards

Internal eval on OSS-Fuzz harness entrypoints measuring unguided vulnerability discovery and how far a found bug is advanced.

Made by Anthropic Finding and exploiting real bugs Tasks kept private Last in a system card Oct 2026 Last model added Oct 2026
Level
Expert Specialists with years of training, often over hours of work
Scored
Checked automatically A program checks the result against an answer key, unit tests or the expected final state.
Answers
Agent task Many steps in a terminal, browser, desktop, app, game or robot.
6
Models scored in lab cards
6
System cards report it, from 1 lab

Claude Opus 5.5 leads with 91.1%

Best score per model as labs report them in their own cards. Labs pick their own settings, so these compare less cleanly than independent runs.

  1. 91.1 Claude Opus 5.5
  2. 85.8 Claude Sonnet 5.5
  3. 79.4 Claude Opus 5
  4. 58.2 Claude Haiku 5.5
  5. 54.5 Claude Sonnet 5
  6. 38.5 Claude Opus 4.8
  1. 1 Claude Opus 5.5 91.1%
  2. 2 Claude Sonnet 5.5 85.8%
  3. 3 Claude Opus 5 79.4%
  4. 4 Claude Haiku 5.5 58.2%
  5. 5 Claude Sonnet 5 54.5%
  6. 6 Claude Opus 4.8 38.5%
#ModelScoreSettingDateSource
1 Claude Opus 5.5 91.1% Sep 2026 Model card
2 Claude Sonnet 5.5 85.8% Sep 2026 Model card
3 Claude Opus 5 79.4% Jul 2026 Model card
4 Claude Haiku 5.5 58.2% Oct 2026 Model card
5 Claude Sonnet 5 54.5% Jun 2026 Model card
6 Claude Opus 4.8 38.5% May 2026 Model card

4 models have held number one since 2023

Lab claims count from the day the card came out, independent runs from the model’s release.

Anthropic
Lab claims Passed 85% in Sep 2026, by Claude Opus 5.5
Claude Opus 5.5 91.1%

The best score passed 85% in Sep 2026

All the scores we have, one dot each, so a model tested at several settings appears more than once.

Reported by the lab in its model card Best so far
0% 20% 40% 60% 80% 100% 2026 Near the ceiling (85%) Claude Opus 5.5 Claude Opus 5 Claude Sonnet 5 Claude Opus 4.8 0% 20% 40% 60% 80% 100% 2026 Near the ceiling (85%) Claude Opus 5.5 Claude Opus 5

Labs report it only in system cards

We read the headline results of 479 launch posts from 51 labs, and none of them list this benchmark. Some system cards do, below.

6 system cards report it, from 1 lab

Besides launch posts, we read the system cards, model cards and technical reports labs publish with a release. They report far more, including safety and frontier-risk tests.

DateDocumentScoreAs the document writes itSection
7 Oct 2026 Claude Haiku 5.5 system card 58.2 Binary Exploitation Benchmark (formerly OSS-Fuzz), vulnerability identification pass@1 58.2% of challenges, 3 control-flow hijacks (3.3.3, Figure 3.3.3.A) Cyber risk
28 Sep 2026 Claude Sonnet 5.5 system card 85.8 Binary Exploitation Benchmark (formerly OSS-Fuzz), vulnerability identification pass@1 85.8% of challenges, 50 control-flow hijacks (3.2.3, Figure 3.2.3.A) Cyber risk
22 Sep 2026 Claude Opus 5.5 system card 91.1 Binary Exploitation Benchmark (formerly OSS-Fuzz), vulnerability identification pass@1 91.1% of challenges (grade above 0), 106 control-flow hijacks (grade 1.0), new harness (3.3.3, Figure 3.3.3.A) Cyber risk
24 Jul 2026 Claude Opus 5 system card 79.4 OSS-Fuzz, non-zero score on 79.4% of about 830 entry points, top score 1.0 on 4 targets and 0.8 on 6 more, safeguards off (3.3.2) Cyber risk
30 Jun 2026 Claude Sonnet 5 system card 54.5 OSS-Fuzz exploit-primitive discovery, any progress (grade above 0) pass@1 54.5% of challenges, 0 control-flow hijacks, top grade 0.8 on two targets, safeguards off (0 with default mitigations) (3.2.2, Figure 3.2.2.A) Cyber risk
28 May 2026 Claude Opus 4.8 system card 38.5 OSS-Fuzz, about 830 entry points from 228 projects, share of targets scoring above 0, from the stated 61.5% that failed to score above 0, safeguards off. Grade 0.4 on 18.1% (4.9% with safeguards), 0.6 once, no control-flow hijack (3.3.4) Cyber risk

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