CVE-2026-113868
Uninitialized memory disclosure and out-of-bounds read in POP3 and SMTP NTLM authentication
Description
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.
INFO
Published Date :
Oct. 20, 2026, 8:17 p.m.
Last Modified :
Oct. 20, 2026, 8:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update Thunderbird to version 158.0.1.
- Configure accounts to use secure authentication methods.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-113868.
| URL | Resource |
|---|---|
| https://bugzilla.mozilla.org/show_bug.cgi?id=2076569 | |
| https://www.mozilla.org/security/advisories/mfsa2026-114/ | |
| https://www.mozilla.org/security/advisories/mfsa2026-115/ |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-113868 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-113868
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-113868 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-113868 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Oct. 20, 2026
Action Type Old Value New Value Added Description 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. Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/113xxx/CVE-2026-113868.json">CVE-2026-113868</a> Added Reference https://bugzilla.mozilla.org/show_bug.cgi?id=2076569 Added Reference https://www.mozilla.org/security/advisories/mfsa2026-114/ Added Reference https://www.mozilla.org/security/advisories/mfsa2026-115/ -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Oct. 20, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-125 Added SSVC {'id': 'CVE-2026-113868', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-10-20T19:41:15.207684Z'}