CVE-2026-47240

ADVISORY - github

Summary

Several Net::IMAP commands accept a "raw data" argument that is sent verbatim after validation to prevent command injection. However, if a server does not support non-synchronizing literals, it may still be possible to inject arbitrary IMAP commands inside non-synchronizing literals.

Details

Raw data arguments support embedded literal values, both synchronizing and non-synchronizing. Non-synchronizing literals can only be safely sent when the server advertises any of the LITERAL+, LITERAL-, or IMAP4rev2 capabilities. But raw data arguments do not verify server support for non-synchronizing literals prior to sending.

Servers without support for non-synchronizing literals could handle them in several different ways: If a server sees a "}\r\n" byte sequence but can't parse the literal bytesize, it may cautiously decide to close the connection, blocking any command injection attacks. However, a server without support for non-synchronizing literals may instead interpret the "+}\r\n" as the end of a malformed command line and respond with a tagged BAD. In that case, the contents of the literal will be interpreted as one or more new pipelined commands, allowing a CRLF command injection attack to succeed.

This affects the following commands' string arguments:

  • criteria for #search and #uid_search
  • search_keys for #sort, #thread, #uid_sort, and #uid_thread
  • attr for #fetch and #uid_fetch

Prior to net-imap v0.6.4, v0.5.14, and v0.4.24, raw data arguments were not validated in any way, so they were also vulnerable to this attack. See CVE-2026-42257 (GHSA-hm49-wcqc-g2xg).

Impact

Fortunately, LITERAL- is supported by most modern IMAP servers. Even without support for non-synchronizing literals, cautious servers may handle invalid literal bytesize by closing the connection . However, servers which handle a non-synchronizing literal just like any other malformed command will enable this vulnerability.

If a developer passes an unvalidated user-controlled input for one of these method arguments, an attacker can append CRLF sequence followed by a new IMAP command (like DELETE mailbox). Although this does not directly enable data exfiltration, it could be combined with other attack vectors or knowledge of the target system's attributes, e.g.: shared mail folders or the application's installed response handlers.

Mitigation

Update to a version of net-imap which validates server support for non-synchronizing literals before sending them.

If upgrading net-imap is not possible:

  • Explicitly validate user-controlled inputs to prevent embedded non-synchronizing literals unless the server supports them.
  • For a simpler, more cautious approach: all embedded literals can be unconditionally prohibited, by checking that string inputs do not contain any CR or LF bytes.
  • Verify that the server advertises any of the LITERAL+, LITERAL-, or IMAP4rev2 capabilities before using untrusted string inputs for the affected "raw data" arguments.
EPSS Score: 0.00193 (0.413)

Common Weakness Enumeration (CWE)

ADVISORY - github

Improper Neutralization of Special Elements used in a Command ('Command Injection')

Improper Neutralization of CRLF Sequences ('CRLF Injection')


GitHub

CREATED

UPDATED

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)

CVSS SCORE

5.8medium
PackageTypeOS NameOS VersionAffected RangesFix Versions
net-imapgem-->=0.6.0,<=0.6.40.6.4.1
net-imapgem--<=0.5.140.5.15

CVSS:4 Severity and metrics

The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.

The vulnerable component is not bound to the network stack and the attacker's path is via read/write/execute capabilities. Either: The attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.

The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: A race condition must be won to successfully exploit the vulnerability. The successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker. The attack may need to be launched multiple times against a single target before being successful. Network injection. The attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).

The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.

Successful exploitation of this vulnerability requires limited interaction by the targeted user with the vulnerable system and the attacker's payload. These interactions would be considered involuntary and do not require that the user actively subvert protections built into the vulnerable system. Examples include: utilizing a website that has been modified to display malicious content when the page is rendered (most stored XSS or CSRF) running an application that calls a malicious binary that has been planted on the system using an application which generates traffic over an untrusted or compromised network (vulnerabilities requiring an on-path attacker).

There is no loss of confidentiality within the Vulnerable System.

There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the Vulnerable System. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the Vulnerable System.

There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.

Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.

There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Chainguard

CREATED

UPDATED

ADVISORY ID

CGA-v4xc-fxjj-9w6p

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-2vxc-4x6h-cj2x

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-35g3-2376-mr42

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-7f2c-6f6r-hxmx

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-jcmf-hh2h-wr2j

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-mp8q-q7cp-8366

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-mx77-7rcx-8wmg

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-p933-3m9m-964v

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-v6h4-qgqh-5vv3

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-wg6r-8q3g-m86g

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-wj69-p77w-8mx6

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY