CVE-2026-115559

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Source
https://cve.org/CVERecord?id=CVE-2026-115559
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-115559.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-115559
Downstream
AZL (2)
Published
2026-11-10T18:39:57Z
Modified
2026-11-11T10:47:23Z
Severity
  • 6.3 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N CVSS Calculator
Summary
imaplib STARTTLS serves plaintext bytes buffered before the handshake as if they came over TLS
Details

IMAP4.starttls() wraps the socket in TLS but leaves self._readbuf, imaplib's own read-ahead buffer, untouched. Any plaintext bytes that arrived in the same recv() as the tagged OK to STARTTLS are returned by readline() after the handshake, so the client treats them as the first responses on the protected channel. A network attacker who cannot break TLS can append forged lines after the server's OK, let the handshake complete with the real server and a valid certificate, and have the client accept the forged CAPABILITY and the forged tagged completion of the next command. This is the STARTTLS command/response injection class of CVE-2011-0411.

Database specific 
{
    "cna_assigner": "PSF",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/115xxx/CVE-2026-115559.json"
}
References

Affected packages

Git / github.com/python/cpython

Affected ranges

Type
GIT
Repo
https://github.com/python/cpython
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
22d79d9840a275ed6ed36cd590dc74edc61765fb
Database specific
Show details 
{
    "extracted_events": [
        {
            "range": [
                {
                    "introduced": "0"
                },
                {
                    "fixed": "3.16.0"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StandardRange"
        }
    ]
}

Affected versions

v0.*
v0.9.8
v0.9.9
v1.*
v1.0.1
v1.0.2
v1.1
v1.1.1
v1.2
v1.2b1
v1.2b2
v1.2b3
v1.2b4
v1.3
v1.3b1
v1.4
v1.4b1
v1.4b2
v1.4b3
v1.5
v1.5.1
v1.5.2
v1.5.2a1
v1.5.2a2
v1.5.2b1
v1.5.2b2
v1.5.2c1
v1.5a1
v1.5a2
v1.5a3
v1.5a4
v1.5b1
v1.5b2
v1.6a1
v1.6a2
v2.*
v2.0
v2.0b1
v2.0b2
v2.0c1
v2.1
v2.1a1
v2.1a2
v2.1b1
v2.1b2
v2.1c1
v2.1c2
v2.2a3
v2.3c1
v2.3c2
v2.4
v2.4a1
v2.4a2
v2.4a3
v2.4b1
v2.4b2
v2.4c1
v3.*
v3.0a1
v3.0a2
v3.0a3
v3.0a4
v3.0a5
v3.0b1
v3.0b2
v3.0b3
v3.0rc1
v3.0rc2
v3.0rc3
v3.1
v3.10.0a1
v3.10.0a7
v3.11.0a3
v3.11.0a4
v3.11.0a5
v3.11.0a6
v3.11.0a7
v3.11.0b1
v3.12.0a1
v3.12.0a2
v3.12.0a3
v3.12.0a4
v3.12.0a5
v3.12.0a6
v3.12.0a7
v3.12.0b1
v3.13.0a1
v3.13.0a2
v3.13.0a3
v3.13.0a4
v3.13.0a5
v3.13.0a6
v3.13.0b1
v3.14.0a1
v3.14.0a2
v3.14.0a3
v3.14.0a4
v3.14.0a5
v3.14.0a6
v3.14.0a7
v3.14.0b1
v3.15.0a1
v3.15.0a2
v3.15.0a3
v3.15.0a4
v3.15.0a5
v3.15.0a6
v3.15.0a7
v3.15.0a8
v3.15.0b1
v3.1a1
v3.1a2
v3.1b1
v3.1rc1
v3.1rc2
v3.2a1
v3.2a2
v3.2a3
v3.2a4
v3.2b1
v3.2b2
v3.2rc1
v3.2rc2
v3.2rc3
v3.3.0a2
v3.3.0a3
v3.3.0a4
v3.3.0b1
v3.3.0b2
v3.3.0rc1
v3.3.0rc2
v3.3.0rc3
v3.4.0a1
v3.4.0a2
v3.4.0a3
v3.4.0a4
v3.4.0b1
v3.4.0b2
v3.4.0b3
v3.5.0a1
v3.5.0a2
v3.5.0a3
v3.5.0a4
v3.5.0b1
v3.6.0a3
v3.6.0b1
v3.7.0a2
v3.9.0a2

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-115559.json"