CVE-2026-42258

IMAP command injection via unvalidated Symbol arguments

Published May 9, 2026 · Updated May 9, 2026

Command injection in Ruby net-imap before 0.4.24, 0.5.0 through 0.5.13, and 0.6.0 through 0.6.3 allows attackers to issue IMAP commands. Generic argument handling writes a Symbol name directly to the IMAP socket as an unquoted system flag, allowing embedded spaces and CRLF to terminate the current command and append another. Exploitation requires a calling application to convert attacker-controlled input to a Symbol and pass it to an IMAP command; injected commands can alter or delete server mailboxes.

CVSS severity5.8
Medium
EPSS probability0.78%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in Ruby net-imap before 0.4.24, 0.5.0 through 0.5.13, and 0.6.0 through 0.6.3 allows attackers to issue IMAP commands. Generic argument handling writes a Symbol name directly to the IMAP socket as an unquoted system flag, allowing embedded spaces and CRLF to terminate the current command and append another. Exploitation requires a calling application to convert attacker-controlled input to a Symbol and pass it to an IMAP command; injected commands can alter or delete server mailboxes.

The record

CVE
CVE-2026-42258
Published
May 9, 2026
Updated
May 9, 2026
Vendor
libwww-perl
Product
net-imap
Classifications
CWE-77, CWE-93
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 9, 2026CVE publishedPublication date reported by the CVE source.
  2. May 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.4.24
  2. Affected versionversion=>= 0.5.0, < 0.5.14
  3. Affected versionversion=>= 0.6.0, < 0.6.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

libwww-perl · net-imapversion=< 0.4.24; version=>= 0.5.0, < 0.5.14; version=>= 0.6.0, < 0.6.4

Published CVSS scores

7.1Red HatCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N
5.8GitHub, Inc.CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N
5.3NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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