CVE-2026-41319

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Source
https://cve.org/CVERecord?id=CVE-2026-41319
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-41319.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-41319
Aliases
Published
2026-04-24T03:07:24.335Z
Modified
2026-07-08T08:14:29.552997555Z
Severity
  • 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N CVSS Calculator
Summary
MailKit has STARTTLS Response Injection via unflushed stream buffer that enables SASL mechanism downgrade
Details

MailKit is a cross-platform mail client library built on top of MimeKit. A STARTTLS Response Injection vulnerability in versions prior to 4.16.0 allows a Man-in-the-Middle attacker to inject arbitrary protocol responses across the plaintext-to-TLS trust boundary, enabling SASL authentication mechanism downgrade (e.g., forcing PLAIN instead of SCRAM-SHA-256). The internal read buffer in SmtpStream, ImapStream, and Pop3Stream is not flushed when the underlying stream is replaced with SslStream during STARTTLS upgrade, causing pre-TLS attacker-injected data to be processed as trusted post-TLS responses. Version 4.16.0 patches the issue.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41319.json",
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-74"
    ]
}
References

Affected packages

Git / github.com/jstedfast/mailkit

Affected ranges

Type
GIT
Repo
https://github.com/jstedfast/mailkit
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
33f045be0f64a255fe153acd640af37d80c0ede3
Database specific 
{
    "source": [
        "AFFECTED_FIELD",
        "CPE_RANGE"
    ],
    "cpe": "cpe:2.3:a:jstedfast:mailkit:*:*:*:*:*:*:*:*",
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "4.16.0"
        }
    ]
}

Affected versions

1.*
1.0.0
1.0.1
1.0.10
1.0.11
1.0.12
1.0.13
1.0.14
1.0.15
1.0.16
1.0.17
1.0.2
1.0.3
1.0.4
1.0.5
1.0.6
1.0.7
1.0.8
1.0.9
1.10.0
1.10.1
1.10.2
1.12.0
1.14.0
1.16.0
1.16.1
1.16.2
1.18.0
1.18.1
1.18.1.1
1.2.0
1.2.1
1.2.10
1.2.11
1.2.11.1
1.2.12
1.2.13
1.2.14
1.2.15
1.2.16
1.2.17
1.2.18
1.2.2
1.2.20
1.2.22
1.2.23
1.2.24
1.2.3
1.2.4
1.2.5
1.2.7
1.2.8
1.2.9
1.20.0
1.22.0
1.4.0
1.4.1
1.4.2
1.6.0
1.8.0
1.8.1
2.*
2.0.0
2.0.1
2.0.2
2.0.4
2.0.5
2.0.6
2.0.7
2.1.0
2.1.0.2
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5.1
2.10.0
2.10.1
2.11.0
2.11.1
2.12.0
2.13.0
2.14.0
2.15.0
2.2.0
2.3.0
2.3.1
2.3.2
2.4.0
2.4.1
2.5.0
2.5.1
2.5.2
2.6.0
2.7.0
2.8.0
2.9.0
3.*
3.0.0
3.1.0
3.1.1
3.2.0
3.3.0
3.4.0
3.4.1
3.4.2
3.4.3
3.5.0
3.6.0
4.*
4.0.0
4.1.0
4.10.0
4.11.0
4.12.0
4.12.1
4.13.0
4.14.0
4.14.1
4.15.0
4.15.1
4.2.0
4.3.0
4.4.0
4.5.0
4.6.0
4.7.0
4.7.1
4.7.1.1
4.8.0
4.9.0

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-41319.json"