Thunderbird CVE-2026-110247

EUVD-2026-99207

2026-10-13 mozilla

GHSA-6c5g-4xv7-7fmm

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Awaiting Data No severity or threat signals available yet. Label will update when CVSS score is published or threat intelligence arrives. Why: No CVSS yet + weak signal (CWE or non-zero EPSS).

No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisCVE.org

Several buffer-growth sites in libmime performed size arithmetic in 32-bit types without overflow checks. On a sufficiently large message the growth guard could fail open, or the buffer could be reallocated smaller than required, and a subsequent memcpy would then write attacker-controlled data across adjacent heap allocations. This vulnerability was fixed in Thunderbird 158.

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Exploit and PoC references, threat intelligence from 22 sources

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Threat Intelligence Overview

EPSS Score

0.2%

Top 94% exploitable

Data Quality

1 sources

Confidence: Low

EUVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity Not scored yet

CISA KEV No

Public POC No

EPSS 0.2%

Patch available No

Active threat No

Deciding rule

No CVSS yet + weak signal (CWE or non-zero EPSS)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Affected Products (CPE)CVE.org

cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

More in Thunderbird

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CVE-2013-1690 HIGH Act Now POC

8.8 Jun 26

Mozilla Firefox before 22.0, Firefox ESR 17.x before 17.0.7, Thunderbird before 17.0.7, and Thunderbird ESR 17.x before

CVE-2013-0758 CRITICAL Emergency POC

9.3 Jan 13

Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and 17.x before 17.0.2, Thunderbird before 17.0.2, Thunderb

CVE-2013-0753 CRITICAL Act Now POC

9.3 Jan 13

Use-after-free vulnerability in the serializeToStream implementation in the XMLSerializer component in Mozilla Firefox b

CVE-2012-3993 CRITICAL Emergency POC

9.3 Oct 10

The Chrome Object Wrapper (COW) implementation in Mozilla Firefox before 16.0, Firefox ESR 10.x before 10.0.8, Thunderbi

CVE-2013-1710 CRITICAL Emergency POC

10.0 Aug 07

The crypto.generateCRMFRequest function in Mozilla Firefox before 23.0, Firefox ESR 17.x before 17.0.8, Thunderbird befo

CVE-2013-0757 CRITICAL Emergency POC

9.3 Jan 13

The Chrome Object Wrapper (COW) implementation in Mozilla Firefox before 18.0, Firefox ESR 17.x before 17.0.2, Thunderbi

CVE-2014-1510 CRITICAL Emergency POC

9.8 Mar 19

The Web IDL implementation in Mozilla Firefox before 28.0, Firefox ESR 24.x before 24.4, Thunderbird before 24.4, and Se

CVE-2014-1511 CRITICAL Emergency POC

9.8 Mar 19

Mozilla Firefox before 28.0, Firefox ESR 24.x before 24.4, Thunderbird before 24.4, and SeaMonkey before 2.25 allow remo

CVE-2016-1960 HIGH Act Now POC

8.8 Mar 13

Integer underflow in the nsHtml5TreeBuilder class in the HTML5 string parser in Mozilla Firefox before 45.0 and Firefox

CVE-2024-9680 CRITICAL Act Now POC

9.8

Alpine Linux: mozjs fixed in 128.3.1-r0

CVE-2015-0816 MEDIUM This Month POC

5.0 Apr 01

Mozilla Firefox before 37.0, Firefox ESR 31.x before 31.6, and Thunderbird before 31.6 do not properly restrict resource

CVE-2013-2566 MEDIUM This Month POC

5.9 Mar 15

The RC4 algorithm, as used in the TLS protocol and SSL protocol, has many single-byte biases, which makes it easier for

Same technique Buffer Overflow

View all

CVE-2017-7269 CRITICAL POC

9.8

CVE-2015-5119 CRITICAL POC

9.8

CVE-2015-3113 CRITICAL POC

9.8

CVE-2011-2462 CRITICAL POC

9.8

CVE-2020-0796 CRITICAL POC

10.0

CVE-2019-11043 CRITICAL POC

9.8

CVE-2009-0927 HIGH POC

8.8

CVE-2012-1889 HIGH POC

8.8

References

Advisories & patches

ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-110247 REF https://bugzilla.mozilla.org/show_bug.cgi?id=2071621 REF https://www.mozilla.org/security/advisories/mfsa2026-109/

Search Externally

GitHub PoC

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