Out of bounds read in IMAP parsing
Summary
| CVE | CVE-2026-4371 |
|---|---|
| State | PUBLISHED |
| Assigner | mozilla |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-03-24 21:16:29 UTC |
| Updated | 2026-07-15 02:22:39 UTC |
| Description | A malicious mail server could send malformed strings with negative lengths, causing the parser to read memory outside the buffer. If a mail server or connection to a mail server were compromised, an attacker could cause the parser to malfunction, potentially crashing Thunderbird or leaking sensitive data. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9. |
Risk And Classification
Primary CVSS: v3.1 7.4 HIGH from ADP
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
EPSS: 0.003600000 probability, percentile 0.282500000 (date 2026-07-15)
Problem Types: CWE-126 | CWE-130 | CWE-126 CWE-126 Buffer Over-read | CWE-130 Improper Handling of Length Parameter Inconsistency
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | DECLARED | 7.4 | HIGH | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H |
| 3.1 | ADP | CVSS | 8.2 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 7.4 | HIGH | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H |
| 3.1 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | Secondary | 8.2 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Mozilla | Thunderbird | All | All | All | All |
| Application | Mozilla | Thunderbird | All | All | All | All |
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| access.redhat.com/security/cve/CVE-2026-4371 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:6917 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:8286 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:8284 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:8288 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| bugzilla.mozilla.org/show_bug.cgi | [email protected] | bugzilla.mozilla.org | Permissions Required |
| access.redhat.com/errata/RHSA-2026:6188 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:8285 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:8287 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:8289 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4371.json | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | security.access.redhat.com | |
| www.mozilla.org/security/advisories/mfsa2026-24 | [email protected] | www.mozilla.org | Vendor Advisory |
| access.redhat.com/errata/RHSA-2026:8850 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| www.mozilla.org/security/advisories/mfsa2026-23 | [email protected] | www.mozilla.org | Vendor Advisory |
| access.redhat.com/errata/RHSA-2026:8290 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:6342 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:8315 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| bugzilla.redhat.com/show_bug.cgi | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | bugzilla.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Rintaro Kobayashi (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| ADP | 2026-03-24T21:01:59.309Z | Reported to Red Hat. |
| ADP | 2026-03-24T20:27:15.198Z | Made public. |
Solutions
ADP: RHSA-2026:8315: Red Hat Enterprise Linux AppStream EUS (v. 10.0)
ADP: RHSA-2026:6342: Red Hat Enterprise Linux AppStream (v. 10)
ADP: RHSA-2026:6917: Red Hat Enterprise Linux AppStream (v. 8)
ADP: RHSA-2026:8285: Red Hat Enterprise Linux AppStream AUS (v. 8.2)
ADP: RHSA-2026:8850: Red Hat Enterprise Linux AppStream AUS (v.8.4), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)
ADP: RHSA-2026:8289: Red Hat Enterprise Linux AppStream AUS (v.8.6), Red Hat Enterprise Linux AppStream E4S (v.8.6), Red Hat Enterprise Linux AppStream TUS (v.8.6)
ADP: RHSA-2026:8288: Red Hat Enterprise Linux AppStream E4S (v.8.8), Red Hat Enterprise Linux AppStream TUS (v.8.8)
ADP: RHSA-2026:8286: Red Hat Enterprise Linux AppStream E4S (v.9.0)
ADP: RHSA-2026:8287: Red Hat Enterprise Linux AppStream E4S (v.9.2)
ADP: RHSA-2026:8290: Red Hat Enterprise Linux AppStream EUS (v.9.4)
ADP: RHSA-2026:8284: Red Hat Enterprise Linux AppStream EUS (v.9.6)
ADP: RHSA-2026:6188: Red Hat Enterprise Linux AppStream (v. 9)
Workarounds
ADP: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.