CVE-2026-54736: Phalcon: Non-constant-time HMAC verification in `Encryption\Crypt::decrypt` (timing side-channel)
Phalcon is a high-performance, full-stack PHP framework. Prior to 5.14.1, Phalcon\Encryption\Crypt::decrypt compares the attacker-supplied HMAC tag against the freshly computed HMAC using PHP/Zephir identity comparison, which lowers to a byte-wise comparison that returns early on the first differing byte. This observable timing discrepancy can allow an attacker to recover a valid tag byte-by-byte and attach it to a chosen IV and ciphertext so that decrypt() accepts tampered encrypted content as authentic. This issue is fixed in version 5.14.1.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Phalconto a version that resolves this vulnerability.Fixed in 5.14.1Patch 5.14.1
Event History
Frequently Asked Questions
What is the severity of CVE-2026-54736?
The severity of CVE-2026-54736 is high with a CVSS score of 8.2.
How do I fix CVE-2026-54736?
To address CVE-2026-54736, upgrade Phalcon to version 5.14.1 or later.
What is the impact of CVE-2026-54736?
CVE-2026-54736 allows for a timing side-channel attack that could enable an attacker to forge HMACs.
Is CVE-2026-54736 present in all versions of Phalcon?
CVE-2026-54736 affects all versions of Phalcon prior to 5.14.1.
What kind of vulnerability is CVE-2026-54736 classified as?
CVE-2026-54736 is classified as a timing side-channel vulnerability related to non-constant-time HMAC verification.