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Response snapshot Oct 27, 2026, 11:07 UTC

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Vulnerabilitythehackernews-openai-compaction-flaw-let-researchers-c6fd9c70afae

OpenAI Compaction Flaw Let Researchers Bypass Hidden Reasoning Protections

OpenAI's compaction feature, which shrinks a long conversation to save space, could be turned into a way to copy a model's hidden reasoning out in plain text, security firm Xint has shown.

At a glance

Exploited
Not known
Severity
Not scored yet
Chance of exploitation
Not estimated
Sources
1 source

What to do

Check the vendor advisory linked from the article for affected versions and fixes.

Read The Hacker News: OpenAI Compaction Flaw Let Researchers Bypass Hidden Reasoning Protections (opens a new tab)

What happened

OpenAI's compaction feature, which shrinks a long conversation to save space, could be turned into a way to copy a model's hidden reasoning out in plain text, security firm Xint has shown.

OpenAI's reasoning models work through a problem before answering, and the service normally returns only the raw reasoning as an encrypted item the user cannot read. The method got past

Sources

  1. Reporting

    The Hacker News: OpenAI Compaction Flaw Let Researchers Bypass Hidden Reasoning Protections (opens a new tab)

    The article reports this vulnerability. It is reporting, not independently primary-confirmed or locally reviewed.

    Published Checked

  2. Reporting

    The Hacker News syndication feed (opens a new tab)

    The RSS/Atom/RDF entry supplied this exact link and any available title, date, and excerpt.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 27). OpenAI Compaction Flaw Let Researchers Bypass Hidden Reasoning Protections. https://kevwire.com/record/thehackernews-openai-compaction-flaw-let-researchers-c6fd9c70afae

MLA

"OpenAI Compaction Flaw Let Researchers Bypass Hidden Reasoning Protections." KEVWire, 27 Oct. 2026, kevwire.com/record/thehackernews-openai-compaction-flaw-let-researchers-c6fd9c70afae.

Chicago

KEVWire. "OpenAI Compaction Flaw Let Researchers Bypass Hidden Reasoning Protections." Last modified October 27, 2026. https://kevwire.com/record/thehackernews-openai-compaction-flaw-let-researchers-c6fd9c70afae.

Evidence summary (plain text)

OpenAI Compaction Flaw Let Researchers Bypass Hidden Reasoning Protections (Oct 27, 2026).
OpenAI's compaction feature, which shrinks a long conversation to save space, could be turned into a way to copy a model's hidden reasoning out in plain text, security firm Xint has shown.

OpenAI's reasoning models work through a problem before answering, and the service normally returns only the raw reasoning as an encrypted item the user cannot read. The method got past
Sources:
The Hacker News: OpenAI Compaction Flaw Let Researchers Bypass Hidden Reasoning Protections: https://thehackernews.com/2026/10/openai-compaction-flaw-let-researchers.html
The Hacker News syndication feed: https://feeds.feedburner.com/TheHackersNews
Record ID: thehackernews-openai-compaction-flaw-let-researchers-c6fd9c70afae.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 11:05 UTC. Ingestion is not an independent editorial investigation.

Syndicated reporting, unreviewed by KEVWire and not independently primary-confirmed. Consult the exact article and any primary disclosure it links.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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