9.1

CVE-2026-113867: Stanza injection in XMPP chat

Awaiting analysis
AliasesDEBIAN-CVE-2026-113867UBUNTU-CVE-2026-113867
Published 20-10-2026Last modified 29-10-2026

Vulnerability summary

CVE-2026-113867 is a critical (CVSS 9.1) Improper Encoding or Escaping of Output vulnerability in thunderbird. EPSS estimates a 0.40% chance of exploitation in the next 30 days, higher than 34.1% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 9.1 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
9.1/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.40%
0%100%
Low · Change unavailable
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
OPENSUSE-SU-2026:12224-1

Timeline

  1. 20-10-2026
    PublishedVulnerability first disclosed.
  2. 29-10-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.40%

Chance of exploitation in the next 30 days

Percentile

34%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

21-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Debian1 product
  • thunderbirdAll versions (No fix recorded) | < 1:153.5.1esr-1~deb12u1 | < 1:153.5.1esr-1~deb13u1
Ubuntu1 product
  • thunderbirdAll versions (No fix recorded)

2 vendors · 2 products

References

7 links