---
id: "CVE-2026-113867"
kind: "vulnerability"
aliases: ["CVE-2026-113867"]
title: "Thunderbird: XMPP replies let remote users inject stanzas as the user"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["desktop-email", "package", "thunderbird", "xmpp"]
not_affected_if: ["mail-only-use", "no-xmpp-account"]
published_at: "2026-10-20T20:17:19+00:00"
first_seen_at: "2026-10-23T21:57:21+00:00"
updated_at: "2026-10-25T05:04:39+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-113867", "first_seen_at": "2026-10-23T21:57:21+00:00"}]
---

# Thunderbird: XMPP replies let remote users inject stanzas as the user

Thunderbird did not escape attribute values when building outgoing XMPP stanzas, and it echoed incoming request values into automatic replies. A remote XMPP user can send a crafted request that makes Thunderbird inject arbitrary stanzas into the user's connection, which the server treats as sent by the user.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed Thunderbird version in Help > About Thunderbird, or run `thunderbird --version` where available.
- Check whether any chat account uses XMPP in the Chat settings of Thunderbird; the bug only affects XMPP accounts.

## Fix

- Update Thunderbird to `158.0.1` or `153.5.1` (the fixed releases named in the source).
- Until updated, disable or avoid XMPP chat accounts in Thunderbird.

## Timeline

- 2026-10-23T21:57:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-113867

## From the sources

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.

---

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