CVE-2026-113867: Vulnerability in Mozilla Thunderbird
Description
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.
Affected software
Mozilla
Thunderbird
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in Mozilla Thunderbird involves improper escaping of attribute values during serialization of outgoing XMPP stanzas. Incoming requests with crafted values were echoed back in automatic replies, enabling a remote attacker to inject arbitrary XMPP stanzas into the user's connection. This injection could be exploited to send messages or alter contact and subscription settings on behalf of the user without their consent. The flaw specifically affects Thunderbird's chat feature using XMPP accounts and was resolved in version 158.0.1.
Potential Impact
An attacker with a remote XMPP account can exploit this vulnerability to inject arbitrary stanzas into the victim's connection, causing the server to process actions as if performed by the victim. This can lead to unauthorized message sending and modification of contact or subscription settings without any user interaction, potentially compromising user communications and contact integrity.
Mitigation Recommendations
This vulnerability has been fixed in Mozilla Thunderbird version 158.0.1. Users and administrators should upgrade to version 158.0.1 or later to remediate this issue. No additional mitigation steps are required once the update is applied.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-10-20T19:14:54.838Z
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-114/","vendor":"Mozilla"}]
Threat ID: 6ad7c23c2cdf04f656561a7e
Added to database: 10/20/2026, 19:34:20 UTC
Last enriched: 10/20/2026, 19:48:22 UTC
Last updated: 10/20/2026, 22:32:58 UTC
Views: 9
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