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Fencer Intel
medium 5.3

CVE-2026-113868 json

Uninitialized memory disclosure and out-of-bounds read in POP3 and SMTP NTLM authentication

published 20d ago modified 18d ago also EUVD-2026-105295

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

When authenticating to a POP3 or SMTP server using NTLM, Thunderbird did not check whether the server's challenge was valid base64. A malicious server could send a challenge that caused Thunderbird to include uninitialized heap memory in its NTLM response, disclosing that memory to the server. A challenge consisting only of base64 padding also caused an out-of-bounds read, crashing Thunderbird. This affected accounts configured to use NTLM or GSSAPI authentication. The uninitialized memory disclosure only affected NTLM. This vulnerability was fixed in Thunderbird 158.0.1 and Thunderbird 153.5.1.

Patch / fix

  • mozilla thunderbird 153.5.1, 158.0.1
  • thunderbird Debian 12 1:153.5.1esr-1~deb12u1
  • thunderbird Debian 13 1:153.5.1esr-1~deb13u1

debian advisories DEBIAN-CVE-2026-113868

  • MozillaThunderbird openSUSE Tumbleweed 153.5.1-1.1

opensuse advisories openSUSE-SU-2026:12224-1

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-113868 updated cvss 5.4

thunderbird: Thunderbird: information disclosure via malformed authentication challenge

  • Red Hat Enterprise Linux 8 thunderbird, thunderbird 140.17.0-1.el10_2 Red Hat Enterprise Linux 9 thunderbird, thunderbird 140.17.0-1.el10_2 Red Hat Enterprise Linux 10 thunderbird 140.17.0-1.el10_2
    affected: no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
20d ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Mozilla Thunderbird

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.