PatchTheCVECVE-2026-113867: Thunderbird did not escape attribute values when serializing outgoing XMPP stanzas
CVE-2026-113867 is a high-severity flaw (CVSS n/a) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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
Why this priority
- No elevated risk signals yet
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | n/a (High) |
| EPSS exploit chance | 0.2% (top 93%) |
| CISA exploited list | No |
| Published | 2026-10-20 |
| Last modified | 2026-10-22 |
Last updated 2026-10-22 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-113867?
No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.
Is CVE-2026-113867 being exploited?
CVE-2026-113867 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-113867 affect?
CVE-2026-113867 affects affected software. Severity is high (CVSS n/a). 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 inje
How urgent is CVE-2026-113867?
Priority 2/100. No elevated risk signals yet.
Software pages
Mozilla Thunderbird vulnerabilities