cakephp/cakephp security advisory

CVE-2026-77634: CakePHP: SmtpTransport vulnerable to CRLF header injection

CVE-2026-77634 is a high-severity header injection vulnerability in the PHP package cakephp/cakephp (CVSS 8.2), published 24 August 2026. It is fixed in 4.5.12, 4.6.5, 5.1.8, 5.2.14 and 5.3.7, one per release line; earlier versions on each line are affected. It can be exploited without an account.

high 8.2 published 2026-08-24 · updated 2026-10-12

Affected versions: >= 4.5.0, < 4.5.12
>= 4.6.0, < 4.6.5
>= 5.0.0, < 5.1.8
>= 5.2.0, < 5.2.14
>= 5.3.0, < 5.3.7
Fixed in: 4.5.12, 4.6.5, 5.1.8, 5.2.14, 5.3.7
Newest release: 5.4.4
Severity: High · CVSS 8.2
Type: Header injection
CWE-93
Exploited in the wild: Not on the CISA KEV list
checked 2026-11-04

Is your cakephp/cakephp version affected?

Run composer show cakephp/cakephp in your project, then enter the version. We check it against this and every other known cakephp/cakephp advisory.

Who can exploit CVE-2026-77634

Access: No account. Anyone who can send a request to an app that uses the affected code.
Conditions: It only works under specific conditions the attacker does not fully control (CVSS rates the attack as high complexity).

CVSS vector (scored by GitHub): CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Your app is only exposed if it uses the affected part of cakephp/cakephp. The advisory below says which part that is. If you are not sure, upgrade anyway: it costs less than finding out.

How to fix CVE-2026-77634 in cakephp/cakephp

Find the installed version: composer show cakephp/cakephp. If you never required it yourself, composer why cakephp/cakephp shows which package pulls it in.
Update it: composer update cakephp/cakephp --with-all-dependencies. You need the fixed version for your release line (4.5.12, 4.6.5, 5.1.8, 5.2.14 and 5.3.7).
If Composer will not go that high, your composer.json constraint is holding it back. Widen it (for example "cakephp/cakephp": "^5.3.7" if you can take that version), or upgrade the package that requires it.
Run composer audit. It reads the same advisory data and should no longer list CVE-2026-77634.
Commit composer.lock and deploy it. On the server, run composer install --no-dev from the lock file, not composer update.

If you cannot upgrade yet

General hardening for header injection issues while the upgrade waits. None of it replaces the fix.

Strip CR and LF characters from any user input that ends up in mail or HTTP headers, including parameter names.
If your app does not use the affected feature, note that in your audit, but still plan the upgrade.

The CVE-2026-77634 advisory

CakePHP is a rapid development framework for PHP. Prior to versions 4.5.12, 4.6.5, 5.1.8, 5.2.14, and 5.3.7 on their respective release lines, custom mail headers added with Message::setHeaders() or Message::addHeaders() do not have CRLF bytes removed, allowing header injection when user-controlled data is used in message headers. This issue is fixed in versions 4.5.12, 4.6.5, 5.1.8, 5.2.14, and 5.3.7.

Description from the CVE record, published by GitHub (the CVE Numbering Authority), via the NVD entry for CVE-2026-77634. Advisory title: “CakePHP: SmtpTransport vulnerable to CRLF header injection”.

References

GitHub advisory GHSA-2qh5-382h-3jpc github.com
Fix commit 0818896 github.com
Fix commit 2afe42b github.com
Fix commit 3e09dae github.com
Fix commit b67b622 github.com

Other cakephp/cakephp advisories

critical CVE-2026-79752: CakePHP: Multiple methods in FunctionsBuilder vulnerable to SQL injection 2026-09-17
critical CVE-2026-77635: CakePHP: FunctionsBuilder::jsonValue() vulerable to SQL injection with PostgresDriver 2026-09-08
medium CVE-2026-48820: CakePHP: View::element() is missing a path containment check 2026-06-26
medium CVE-2026-23643: CakePHP PaginatorHelper::limitControl() vulnerable to reflected cross-site-scripting 2026-01-16
critical CVE-2023-22727: CakePHP Database\\Query::offset() and limit() methods are vulnerable to SQL injection 2023-01-20
high CVE-2020-35239: CakePHP allows method override parameters to bypass CSRF checks 2022-05-24

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Where this data comes from

Affected and fixed versions: the Packagist security advisories API (GitHub Advisory Database and FriendsOfPHP), the same data composer audit uses. Synced 2026-11-03.
Description, score, weakness and references: NIST National Vulnerability Database (NVD), checked 2026-11-04. This product uses data from the NVD API but is not endorsed or certified by the NVD.
Exploited-in-the-wild status: the CISA Known Exploited Vulnerabilities catalog, checked 2026-11-04.
Compiled by Daniel Lasek at Laskyr from the sources above. The summary, “who can exploit it”, “how to fix it” and hardening sections are our plain-English reading of the record and are generated from it. The quoted description is the record's own text. Spot an error? Tell us.