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VulnerabilityPublished

CVE-2026-73299: microsoft prompty · Code Injection

Affects microsoft promptySource CVE Database V5

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Not known to be exploited · CVSS 10.0 Critical : upgrade to 2.0.0-beta.5 or 0.1.5 as a priority.

Data as of 9 Nov 2026, 23:24 UTC

CVSS 3.1 base score
10.0Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.7% chance of exploitation in 30 days – higher than 78% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.0.0-beta.5, 0.1.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

What to do

Upgrade microsoft prompty to 2.0.0-beta.5 or 0.1.5.

Affected software

ProductAffectedFixed in
microsoftpromptyAffected
  • >=2.0.0-alpha.1 <2.0.0-beta.5
Fixed in
  • 2.0.0-beta.5
microsoftpromptyAffected
  • <0.1.5
Fixed in
  • 0.1.5

AI-suggested

This vulnerability is fixed in Prompty versions 0.1.5 and 2.0.0-beta.5. Users should upgrade to these versions or later to remediate the issue. Patch status is not explicitly confirmed in the vendor advisory, but the description states the issue is fixed in these versions. No other mitigation guidance is provided.

Description

Prompty is a markdown file format (.prompty) for LLM prompts. Prior to 0.1.5 and 2.0.0-beta.5, the TypeScript Nunjucks renderer evaluated untrusted .prompty template bodies with unrestricted JavaScript member access. An attacker-controlled template could traverse constructor and prototype properties to execute JavaScript in the host Node.js process. This issue is fixed in versions 0.1.5 and 2.0.0-beta.5.

References

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