CVE-2026-113868
published 2026-10-20CVE-2026-113868: 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…
PriorityP429medium5.3CVSS 3.1
AVNACHPRLUINSUCNINAH
EPSS
0.43%
36.7th percentile
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.
Affected
3 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| mozilla | thunderbird | < Thunderbird 158.0.1 | Thunderbird 158.0.1 |
| mozilla | thunderbird | < Thunderbird 153.5.1 | Thunderbird 153.5.1 |
| mozilla | thunderbird | — | — |
CVSS provenance
nvdv3.15.3MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
vendor_redhat5.3MEDIUM
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Red Hat
thunderbird: Thunderbird: information disclosure via malformed authentication challenge
vendor_redhat·2026-10-20·CVSS 5.3
CVE-2026-113868 [MEDIUM] CWE-908 thunderbird: Thunderbird: information disclosure via malformed authentication challenge
thunderbird: Thunderbird: information disclosure via malformed authentication challenge
A flaw was found in Thunderbird. When authenticating to an email server using NT LAN Manager (NTLM) or Generic Security Services Application Program Interface (GSSAPI), the client fails to properly validate the server's authentication challenge format. A malicious server can exploit this flaw by sending a specially crafted challenge, causing Thunderbird to return uninitialized memory and leading to information disclosure. A malformed challenge can also trigger an out-of-bounds read that crashes the client, resulting in a Denial of Service (DoS).
Package: thunderbird (Red Hat Enterprise Linux 10) - Fix deferred
Package: thunderbird (Red Hat Enterprise Linux 8) - Fix deferred
Package: thunderbird (Red
Mozilla
Mozilla Foundation Security Advisory 2026-114: CVE-2026-113868
vendor_mozilla
CVE-2026-113868 Mozilla Foundation Security Advisory 2026-114: CVE-2026-113868
Mozilla Foundation Security Advisory 2026-114
CVE: CVE-2026-113868
Product: Thunderbird
Impact: low
Fixed in: Thunderbird 158.0.1
Mozilla
Mozilla Foundation Security Advisory 2026-115: CVE-2026-113868
vendor_mozilla
CVE-2026-113868 Mozilla Foundation Security Advisory 2026-115: CVE-2026-113868
Mozilla Foundation Security Advisory 2026-115
CVE: CVE-2026-113868
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 153.5.1
GHSA
When authenticating to a POP3 or SMTP server using NTLM, Thunderbird did not check whether the server's challenge was valid base64.
ghsa_unreviewed·2026-10-20
CVE-2026-113868 [MEDIUM] CWE-125 When authenticating to a POP3 or SMTP server using NTLM, Thunderbird did not check whether the server's challenge was valid base64.
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.
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-113868 thunderbird: Thunderbird: information disclosure via malformed authentication challenge [fedora-all]
bugzilla·2026-10-27·CVSS 5.3
CVE-2026-113868 [MEDIUM] CVE-2026-113868 thunderbird: Thunderbird: information disclosure via malformed authentication challenge [fedora-all]
CVE-2026-113868 thunderbird: Thunderbird: information disclosure via malformed authentication challenge [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
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 aut
Bugzilla
CVE-2026-113868 thunderbird: Thunderbird: information disclosure via malformed authentication challenge
bugzilla·2026-10-20·CVSS 5.3
CVE-2026-113868 [MEDIUM] CVE-2026-113868 thunderbird: Thunderbird: information disclosure via malformed authentication challenge
CVE-2026-113868 thunderbird: Thunderbird: information disclosure via malformed authentication challenge
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.
2026-10-20
Published