How severe is CVE-2026-77634?

CVE-2026-77634 has a CVSS 4.0 base score of 8.2, rated high severity.

Is CVE-2026-77634 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-77634?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-77634 published?

CVE-2026-77634 was published on 2026-08-24 and last updated on 2026-09-09.

CVE-2026-77634

CVE-2026-77634 is a high-severity vulnerability with a CVSS 4.0 base score of 8.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-93.

Key facts

Severity: High (CVSS 4.0 base score 8.2)
EPSS exploit prediction: 1% (44th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-93
Published: 2026-08-24
Last modified: 2026-09-09

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.

Frequently asked questions

What is CVE-2026-77634?: 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.
How severe is CVE-2026-77634?: CVE-2026-77634 has a CVSS 4.0 base score of 8.2, rated high severity.
Is CVE-2026-77634 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-77634?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-77634 published?: CVE-2026-77634 was published on 2026-08-24 and last updated on 2026-09-09.

References

Other CWE-93 (CRLF Injection) vulnerabilities

CVE-2026-77550 — Critical (CVSS 10.0): A malicious actor with access to the network could exploit an Improper Neutralization of CRLF Sequences vulnerability…
CVE-2024-51501 — Critical (CVSS 10.0): Refit is an automatic type-safe REST library for .NET Core, Xamarin and .NET The various header-related Refit…
CVE-2026-100717 — Critical (CVSS 9.9): froxlor is a server administration panel. In versions 2.3.10 and earlier, Validate::validateUrl rejects carriage return…
CVE-2026-90937 — Critical (CVSS 9.9): froxlor versions before 2.2.5 fail to validate newline characters in subdomain redirect URLs, allowing authenticated…
CVE-2026-70615 — Critical (CVSS 9.9): boringproxy through 0.10.0 contains a newline injection vulnerability that allows authenticated low-privileged users…
CVE-2026-45372 — Critical (CVSS 9.9): cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, when cpp-httplib's…

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