CVE-2023-1945Network attack vector

Application crash via uninitialized Safe Browsing prefix set

Published Jun 2, 2023 · Updated Jan 9, 2025

Memory corruption in Mozilla Firefox ESR and Thunderbird before 102.10 allows attackers to crash the application through Safe Browsing data. The nsUrlClassifierPrefixSet constructor leaves its variable-length prefix storage uninitialized, so destruction can free or access invalid memory after an unexpected update. Triggering requires malformed data from a trusted Safe Browsing provider or a malicious intermediary; the established consequence is an application crash.

CVSS severity6.5
Medium
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in Mozilla Firefox ESR and Thunderbird before 102.10 allows attackers to crash the application through Safe Browsing data. The nsUrlClassifierPrefixSet constructor leaves its variable-length prefix storage uninitialized, so destruction can free or access invalid memory after an unexpected update. Triggering requires malformed data from a trusted Safe Browsing provider or a malicious intermediary; the established consequence is an application crash.

The record

CVE
CVE-2023-1945
Published
Jun 2, 2023
Updated
Jan 9, 2025
Vendor
Mozilla
Product
Thunderbird
Classifications
CWE-787, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 2, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 9, 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 <102.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Thunderbirdversion=unspecified <102.10
Mozilla · Firefox ESRversion=unspecified <102.10

Published CVSS scores

6.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/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.

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

CWE-787Out-of-bounds Write
T1499.004Application or System Exploitation

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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