CVE-2024-4770Public exploitNetwork attack vector

Application crash via uninitialized CFF font fields

Published May 14, 2024 · Updated Feb 13, 2025

Use-after-free in Mozilla Firefox before 126, Firefox ESR before 115.11, and Thunderbird before 115.11 allows remote attackers to cause a crash. _cairo_cff_font_fallback_create leaves several cairo_cff_font_t members uninitialized, so cairo_cff_font_destroy frees the uninitialized fd_local_sub_bias pointer. A crafted page must reach CFF fallback font generation and a user must save it as PDF; successful triggering interrupts the client with a crash.

CVSS severity8.8
High
EPSS probability0.59%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Mozilla Firefox before 126, Firefox ESR before 115.11, and Thunderbird before 115.11 allows remote attackers to cause a crash. _cairo_cff_font_fallback_create leaves several cairo_cff_font_t members uninitialized, so cairo_cff_font_destroy frees the uninitialized fd_local_sub_bias pointer. A crafted page must reach CFF fallback font generation and a user must save it as PDF; successful triggering interrupts the client with a crash.

The record

CVE
CVE-2024-4770
Published
May 14, 2024
Updated
Feb 13, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-416
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 14, 2024CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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=- <126
  2. Affected versionversion=unspecified <126

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=- <126; version=unspecified <126
Mozilla · Thunderbirdversion=- <115.11; version=unspecified <115.11
Mozilla · Firefox ESRversion=- <115.11; version=unspecified <115.11

Published CVSS scores

8.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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.

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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 exploitPublished

Weakness, pattern, technique

CWE-416Use After Free

Public exploit references

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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