TI-2026-77011 Aliases CVE-2026-113868 GHSA-v77j-vmg8-85hq

Uninitialized memory disclosure in Thunderbird NTLM authentication

LOW 24CWE-125Published 2026-10-20 · Updated 2026-10-20

Key facts

Attack vector: Network
Privileges required: Low
User interaction: None
Attack complexity: High
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Partial Red Hat: 3 without a fix

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-125 and the CVSS impact.

Summary

Mozilla Thunderbird is affected, and the fixed releases are 153.5.1 and 158.0.1. When authenticating to a POP3 or SMTP server with NTLM, Thunderbird did not check whether the server's challenge was valid base64, so a malicious server can send a challenge that makes it include uninitialized heap memory in its NTLM response. A challenge consisting only of base64 padding also causes an out-of-bounds read (CWE-125) that crashes Thunderbird.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00425 37th percentileScored 2026-11-07

Fix Partial Thunderbird (Mozilla): 153.5.1, 158.0.1Red Hat: 3 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Mozilla	Thunderbird	—	153.5.1, 158.0.1	Patch available	CNA

Thunderbird VendorMozilla Affected — Fixed in 153.5.1, 158.0.1 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:mozilla:thunderbird::::::::	—	—	Mozilla

cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions — — ·Mozilla

Remediation

Update Mozilla Thunderbird to 153.5.1 or 158.0.1, which fix the flaw. Red Hat Enterprise Linux 8, 9 and 10 are affected, and the sources list no fixed version for them.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Fix · CNA Thunderbird (Mozilla) Fixed in 153.5.1, 158.0.1

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Enterprise Linux 10	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 8	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 9	Affected	No fix yet: Fix deferred

Timeline

2026-10-20 Threatist record created from CVE-2026-113868
2026-10-21 Alias added: GHSA-v77j-vmg8-85hq
2026-10-21 Affected versions changed · Red Hat
2026-10-21 CVSS score added · Red Hat

References

Other 3

TI-2024-08981 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.8
TI-2022-09832 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.6
TI-2019-08769 Improper input validation in Mozilla Firefox ESR KEVCVSS 3.1CRITICAL 10.0
TI-2010-03577 Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before… KEVCVSS 3.1CRITICAL 9.8
TI-2023-04799 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
TI-2023-04477 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8

See all 4204 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences