CVE-2023-6863Network attack vector

Unspecified shutdown impact via non-virtual base deletion

Published Dec 19, 2023 · Updated Feb 13, 2025

Undefined behavior in Mozilla Firefox before 121, Firefox ESR before 115.6, and Thunderbird before 115.6 allows unspecified impact. ShutdownObserver deletes cached nsString objects through nsAString base pointers whose static type lacks a virtual destructor, making each deletion undefined. The fault is reached while graphics-driver strings are cleared during application shutdown; Mozilla calls it a minor shutdown security issue but publishes no concrete consequence.

CVSS severity8.8
High
EPSS probability1.04%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Undefined behavior in Mozilla Firefox before 121, Firefox ESR before 115.6, and Thunderbird before 115.6 allows unspecified impact. ShutdownObserver deletes cached nsString objects through nsAString base pointers whose static type lacks a virtual destructor, making each deletion undefined. The fault is reached while graphics-driver strings are cleared during application shutdown; Mozilla calls it a minor shutdown security issue but publishes no concrete consequence.

The record

CVE
CVE-2023-6863
Published
Dec 19, 2023
Updated
Feb 13, 2025
Vendor
Mozilla
Product
Firefox
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 19, 2023CVE 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=unspecified <121

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <121
Mozilla · Thunderbirdversion=unspecified <115.6
Mozilla · Firefox ESRversion=unspecified <115.6

Published CVSS scores

8.8NIST NVDCVSS: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.

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

No sourced classifications are available.

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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