CVE-2020-6793Network attack vector

Memory disclosure via uninitialized header start offset

Published Mar 2, 2020 · Updated Aug 4, 2024

Out-of-bounds read in Thunderbird before 68.5 allows remote attackers to disclose process memory through a crafted email message. nsParseMailMessageState::FinalizeHeaders leaves m_headerstartpos uninitialized when the envelope position is zero, then uses that offset during header-buffer processing. A recipient must interact with the crafted message; the documented consequence is memory disclosure, with no integrity or availability impact.

CVSS severity6.5
Medium
EPSS probability1.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Thunderbird before 68.5 allows remote attackers to disclose process memory through a crafted email message. nsParseMailMessageState::FinalizeHeaders leaves m_headerstartpos uninitialized when the envelope position is zero, then uses that offset during header-buffer processing. A recipient must interact with the crafted message; the documented consequence is memory disclosure, with no integrity or availability impact.

The record

CVE
CVE-2020-6793
Published
Mar 2, 2020
Updated
Aug 4, 2024
Vendor
Mozilla
Product
Thunderbird
Classifications
CWE-125
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 2, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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 <68.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Thunderbirdversion=unspecified <68.5

Published CVSS scores

6.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
6.1Red HatCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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.

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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 exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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