Vulnerability · CVE-2026-113867
Thunderbird did not escape attribute values when serializing outgoing XMPP stanzas.
Published Oct 20, 2026 · catalog updated Oct 22, 2026 · Mozilla Thunderbird
Check if you run it
No confirmed exploitation is on record for CVE-2026-113867. EPSS is 0.18%. Act only if a listed version of Mozilla Thunderbird is installed.
Gaps on this record
- No version range is stored. A customer cannot check an installed version against this record.
- No vendor fix or required action is stored. Compare the linked advisory before you change production.
- Severity
- Unknown—
- Known exploitation
- Not in CISA/VulnCheck KEV
- EPSS
- 0.18%
- Remediation
- Advisory link
- Affected products
- vendor Mozilla Thunderbird
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.
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.
- vendor Mozilla Thunderbirdversion unspecified
How to fix CVE-2026-113867
Recommended remediation
A patch or advisory reference is linked. Open the original publisher for availability by product version.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
No confirmed exploitation is on record for CVE-2026-113867. EPSS is 0.18%. Act only if a listed version of Mozilla Thunderbird is installed.
Which versions are affected?
Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.
What should an analyst verify?
No weakness class is stored. EPSS 0.18%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Oct 20, 2026 · NIST NVD
Detected
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 conta
Oct 22, 2026 · NIST NVD
Updated
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 conta
Sources
- BSI CERT-BundGovernment advisoryCVE-2026-113867
Mozilla Produkte (Thunderbird, Firefox ESR und Firefox): Mehrere Schwachstellen
wid.cert-bund.de - CVE.orgVulnerability recordCVE-2026-113867
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 con
cve.org - FIRST EPSSExploitation probabilityCVE-2026-113867
30-day exploitation probability 0.18%
first.org - Mozilla Security AdvisoriesVendor advisoryCVE-2026-113867
Security Vulnerabilities fixed in Thunderbird 153.5.1 — Mozilla
mozilla.org - NIST NVDVulnerability recordCVE-2026-113867
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 con
nvd.nist.gov
References
Freshness
Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.