How severe is CVE-2026-77634?

No CVSS score has been assigned to CVE-2026-77634 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-77634?

CVE-2026-77634 affects the following packages: cakephp/cakephp (Packagist), cakephp/cakephp (Packagist), cakephp/cakephp (Packagist), cakephp/cakephp (Packagist), cakephp/cakephp (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-77634?

Update cakephp/cakephp to 4.5.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-77634 is resolved across your whole dependency graph.

How do I detect CVE-2026-77634 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for cakephp/cakephp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-77634 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-77634 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-77634 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-77634?

CVE-2026-77634 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 44th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-77634?

CVE-2026-77634 is classified as CWE-93 (CWE-93). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-77634 published, and has it been updated?

CVE-2026-77634 was published on August 24, 2026 and was last updated on September 11, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-77634: cakephp — Fixed in 4.5.12

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-77634.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk+0.23%

Lower risk than most CVEs44th percentile — riskier than 44% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

5 pkgs affected

🐘cakephp/cakephp🐘cakephp/cakephp🐘cakephp/cakephp🐘cakephp/cakephp🐘cakephp/cakephp

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

5 total 5 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`cakephp/cakephp`	≥ 4.5.0&&< 4.5.12	4.5.12`composer require cakephp/cakephp:^4.5.12`
🐘Packagist	`cakephp/cakephp`	≥ 4.6.0&&< 4.6.5	4.6.5`composer require cakephp/cakephp:^4.6.5`
🐘Packagist	`cakephp/cakephp`	≥ 5.0.0&&< 5.1.9	5.1.9`composer require cakephp/cakephp:^5.1.9`
🐘Packagist	`cakephp/cakephp`	≥ 5.2.0&&< 5.2.14	5.2.14`composer require cakephp/cakephp:^5.2.14`
🐘Packagist	`cakephp/cakephp`	≥ 5.3.0&&< 5.3.7	5.3.7`composer require cakephp/cakephp:^5.3.7`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for cakephp/cakephp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update cakephp/cakephp to 4.5.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-77634 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

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CVE-2026-77634 — cakephp