CVE-2026-77634Network attack vector

Mail header injection via unstripped CRLF bytes

Published Aug 24, 2026 · Updated Aug 24, 2026

CRLF injection in CakePHP allows remote attackers to inject arbitrary mail headers through user-controlled custom header values. Message::setHeaders() and Message::addHeaders() pass custom header values to SmtpTransport without removing carriage-return and line-feed bytes. Exploitation requires an application to place attacker-controlled data in a custom mail header, enabling alteration of the emitted message's header structure.

CVSS severity8.2
High
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CRLF injection in CakePHP allows remote attackers to inject arbitrary mail headers through user-controlled custom header values. Message::setHeaders() and Message::addHeaders() pass custom header values to SmtpTransport without removing carriage-return and line-feed bytes. Exploitation requires an application to place attacker-controlled data in a custom mail header, enabling alteration of the emitted message's header structure.

The record

CVE
CVE-2026-77634
Published
Aug 24, 2026
Updated
Aug 24, 2026
Vendor
CakePHP
Product
CakePHP
Classifications
CWE-93, T1565
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 24, 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=>= 4.5.0, < 4.5.12
  2. Affected versionversion=>= 4.6.0, < 4.6.5
  3. Affected versionversion=>= 5.0.0, < 5.1.9
  4. Affected versionversion=>= 5.2.0, < 5.2.14
  5. Affected versionversion=>= 5.3.0, < 5.3.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

CakePHP · CakePHPversion=>= 4.5.0, < 4.5.12; version=>= 4.6.0, < 4.6.5; version=>= 5.0.0, < 5.1.9; version=>= 5.2.0, < 5.2.14; version=>= 5.3.0, < 5.3.7

Published CVSS scores

8.2GitHub CNACVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')
T1565Data Manipulation

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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