CVE-2024-9393Network attack vector

Cross-origin PDF disclosure via multipart response handling

Published Oct 1, 2024 · Updated Nov 3, 2025

Origin validation failure in Mozilla Firefox, Firefox ESR, and Thunderbird allows remote attackers to read cross-origin PDF content. Multipart PDF responses are passed to PDF.js, where attacker-controlled JavaScript executes with the privileged resource://pdf.js origin instead of the response origin. Crafted content must reach a browser or browser-like context; desktop Site Isolation limits disclosure to same-site PDFs, and Thunderbird disables scripting during normal email reading.

CVSS severity7.5
High
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Origin validation failure in Mozilla Firefox, Firefox ESR, and Thunderbird allows remote attackers to read cross-origin PDF content. Multipart PDF responses are passed to PDF.js, where attacker-controlled JavaScript executes with the privileged resource://pdf.js origin instead of the response origin. Crafted content must reach a browser or browser-like context; desktop Site Isolation limits disclosure to same-site PDFs, and Thunderbird disables scripting during normal email reading.

The record

CVE
CVE-2024-9393
Published
Oct 1, 2024
Updated
Nov 3, 2025
Vendor
Mozilla
Product
Firefox
Classifications
T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 1, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <131

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <131
Mozilla · Thunderbirdversion=unspecified <128.3; version=unspecified <131
Mozilla · Firefox ESRversion=unspecified <115.16; version=unspecified <128.3

Published CVSS scores

7.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
7.5NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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