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CVE-2026-118174

Displaying a message could load an attacker-chosen URL through an OpenPGP key attachment

When a message containing an OpenPGP key attachment was displayed, Thunderbird automatically loaded the attachment's content to offer importing the key. A sender could mark the attachment as an external attachment pointing to an arbitrary URL, which Thunderbird then loaded without any user interaction, bypassing remote content blocking. On Windows, a URL pointing to an attacker-controlled network share could leak the user's NTLM credentials. The NTLM credential leak only affects Thunderbird on Windows. On other operating systems, the issue allowed a remote request that bypassed remote content blocking. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Thunderbird
CVE-2024-5700

Mozilla: Memory safety bugs fixed in Firefox 127, Firefox ESR 115.12, and Thunderbird 115.12

Memory safety bugs present in Firefox 126, Firefox ESR 115.11, and Thunderbird 115.11. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 127, Firefox ESR < 115.12, and Thunderbird < 115.12.

CVSS 3.1 · 7 High EPSS < 1% KEV · Not listed
Vendors
Mozilla Redhat
Products
Firefox Firefox Esr Thunderbird and 5 more
CVE-2024-3863

Mozilla: Download Protections were bypassed by .xrm-ms files on Windows

The executable file warning was not presented when downloading .xrm-ms files. *Note: This issue only affected Windows operating systems. Other operating systems are unaffected.* This vulnerability affects Firefox < 125, Firefox ESR < 115.10, and Thunderbird < 115.10.

CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-74985

Privilege escalation in the Enterprise Policies component

Privilege escalation in the Enterprise Policies component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.

CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-109763

Mitigation bypass in the File Handling component

Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

CVSS 3.1 · 5.4 Medium EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-113867

Stanza injection in XMPP chat

Thunderbird did not escape attribute values when serializing outgoing XMPP stanzas. Because values from incoming requests were echoed back in automatic replies, a remote XMPP user could send a crafted request that caused Thunderbird to inject arbitrary stanzas into the user's connection, which the server would then process as if sent by the user. This could be used to send messages or change contact and subscription settings on behalf of the user, without any interaction. This bug only affects Thunderbird's chat feature with XMPP accounts. This vulnerability was fixed in Thunderbird 158.0.1 and Thunderbird 153.5.1.

CVSS 3.1 · 9.1 Critical EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Thunderbird
CVE-2026-74969

Race condition, use-after-free in the Layout: Text and Fonts component

Race condition, use-after-free in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-74989

Internally found bugs fixed in Firefox 154

Internally found bugs present in Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154.

CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-74988

Internally found bugs fixed in Firefox ESR 153.1 and Firefox 154

Internally found bugs present in Firefox ESR 153.0 and Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.

CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-74990

Internally found bugs fixed in Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154

Internally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-74987

Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154

Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-74949

Use-after-free in the Graphics: Canvas2D component

Use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-74946

Information disclosure due to incorrect boundary conditions in the Graphics: CanvasWebGL component

Information disclosure due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-113869

Use-after-free in S/MIME decryption during a security device password prompt

When Thunderbird asked for a security device password (for example a smartcard PIN or the Primary Password) while decrypting an S/MIME message, the message load could finish or be cancelled while the prompt was open. This freed the message decoder while it was still in use, causing a use-after-free and a potentially exploitable crash. This vulnerability was fixed in Thunderbird 158.0.1 and Thunderbird 153.6.

CVSS 3.1 · 5.4 Medium EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Thunderbird
CVE-2026-110247

Integer overflow in libmime buffer growth could lead to heap corruption

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 and Thunderbird 153.6.

CVSS 3.1 · 8.4 High EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Thunderbird
CVE-2026-100801

Privilege escalation in the DLL Services component

Privilege escalation in the DLL Services component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 159, Firefox ESR 153.6, Thunderbird 159, Thunderbird 153.6, Firefox 157, and Firefox ESR 140.17.

CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-109782

Mitigation bypass in the File Handling component

Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox ESR 153.5 and Thunderbird 153.5.

CVSS 3.1 · 8.3 High EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-113868

Uninitialized memory disclosure and out-of-bounds read in POP3 and SMTP NTLM authentication

When authenticating to a POP3 or SMTP server using NTLM, Thunderbird did not check whether the server's challenge was valid base64. A malicious server could send a challenge that caused Thunderbird to include uninitialized heap memory in its NTLM response, disclosing that memory to the server. A challenge consisting only of base64 padding also caused an out-of-bounds read, crashing Thunderbird. This affected accounts configured to use NTLM or GSSAPI authentication. The uninitialized memory disclosure only affected NTLM. This vulnerability was fixed in Thunderbird 158.0.1 and Thunderbird 153.5.1.

CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Thunderbird
CVE-2026-8974

Memory safety bugs fixed in Thunderbird 140.11 and Thunderbird 151

Memory safety bugs present in Thunderbird 140.10 and Thunderbird 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird
CVE-2026-8973

Memory safety bugs fixed in Thunderbird 151

Memory safety bugs present in Thunderbird 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 151 and Thunderbird 151.

CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed
Vendors
Mozilla
Products
Firefox Thunderbird