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CVE-2026-55558

Опубликовано: 20 авг. 2026
Источник: ubuntu
Приоритет: medium
CVSS3: 5.9

Описание

aiosmtplib is an asynchronous SMTP client for use with asyncio. Prior to 5.1.2, SMTPProtocol.start_tls in src/aiosmtplib/protocol.py consumes the server's 220 response and starts the TLS handshake without clearing SMTPProtocol._buffer. An active network attacker can place attacker-chosen SMTP response lines after the plaintext 220 response in the same network segment. The method then calls loop.start_tls; those bytes survive the transport upgrade and are parsed as the first response from inside the TLS session, desynchronizing subsequent SMTP command and response pairs. Connections using start_tls=True or opportunistic STARTTLS are affected, while connections using use_tls=True are not. This issue is fixed in version 5.1.2.

РелизСтатусПримечание
devel

needs-triage

esm-apps/jammy

needs-triage

esm-apps/resolute

needs-triage

jammy

needs-triage

noble

DNE

resolute

needs-triage

upstream

needs-triage

Показывать по

Ссылки на источники

5.9 Medium

CVSS3

Связанные уязвимости

CVSS3: 5.9
nvd
16 дней назад

aiosmtplib is an asynchronous SMTP client for use with asyncio. Prior to 5.1.2, SMTPProtocol.start_tls in src/aiosmtplib/protocol.py consumes the server's 220 response and starts the TLS handshake without clearing SMTPProtocol._buffer. An active network attacker can place attacker-chosen SMTP response lines after the plaintext 220 response in the same network segment. The method then calls loop.start_tls; those bytes survive the transport upgrade and are parsed as the first response from inside the TLS session, desynchronizing subsequent SMTP command and response pairs. Connections using start_tls=True or opportunistic STARTTLS are affected, while connections using use_tls=True are not. This issue is fixed in version 5.1.2.

CVSS3: 5.9
debian
16 дней назад

aiosmtplib is an asynchronous SMTP client for use with asyncio. Prior ...

CVSS3: 5.9
github
9 дней назад

aiosmtplib: STARTTLS response injection

5.9 Medium

CVSS3