Which versions of Phalcon are affected by CVE-2026-54736?

Phalcon PHP framework versions prior to 5.14.1 contain a timing side-channel vulnerability allowing attackers to forge authentication tags and bypass data integrity protections without detection.. A patch is available.

Is there a public PoC exploit available for CVE-2026-54736?

Yes, a public proof-of-concept exploit is available for CVE-2026-54736. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate CVE-2026-54736?

24 hours: Inventory all systems running Phalcon and document current versions. 7 days: Upgrade to Phalcon 5.14.1 or later and conduct integration testing on updated systems. 30 days: Verify deployment across all environments and validate encryption operations.

Phalcon CVE-2026-54736

Q: What is the CVSS score of CVE-2026-54736?

CVE-2026-54736 has a CVSS 4.0 base score of 8.2 (High). CVSS vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.1%.

EUVD-2026-43097 HIGH

Observable Timing Discrepancy (CWE-208)

2026-07-10 GitHub_M

GHSA-8jqh-95g6-7jpj

PHP Information Disclosure Suse Cphalcon Phalcon

8.2

CVSS 4.0 · Vendor: GitHub_M

Severity by source

Vendor (GitHub_M) PRIMARY

8.2 HIGH

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

5.9 MEDIUM

Network-reachable timing oracle with no auth (AV:N/PR:N) but many samples needed against jitter (AC:H); impact is forged-content acceptance, so I:H with C:N/A:N.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

SUSE

MEDIUM

qualitative

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Patch available

Jul 10, 2026 - 23:02 EUVD

Analysis Generated

Jul 10, 2026 - 21:53 vuln.today

DescriptionCVE.org

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.

AnalysisAI

Authentication-bypass via timing side-channel in Phalcon's Crypt::decrypt (cphalcon PHP framework prior to 5.14.1) allows remote attackers to forge valid HMAC tags and have tampered ciphertext accepted as authentic. Because the HMAC verification uses PHP/Zephir identity comparison that short-circuits on the first mismatching byte, an attacker who can observe response timing can recover a valid tag byte-by-byte and break the encrypt-then-MAC integrity guarantee. There is no public exploit identified at time of analysis and it is not in CISA KEV, but the flaw is confirmed and patched by the vendor in 5.14.1.

Technical ContextAI

Phalcon is a high-performance, full-stack PHP framework implemented as a C/Zephir extension. The affected component is Phalcon\Encryption\Crypt, which provides authenticated symmetric encryption using an encrypt-then-HMAC construction. The root cause is CWE-208 (Observable Timing Discrepancy): the code compares the attacker-supplied HMAC tag to the server-computed HMAC using Zephir/PHP identity/equality comparison, which lowers to a non-constant-time byte-wise memory comparison that returns as soon as two bytes differ. Constant-time comparison (e.g. hash_equals) is required for MAC verification precisely to avoid this leak. The CPE cpe:2.3:a:phalcon:cphalcon:*:*:*:*:*:*:*:* confirms the cphalcon extension is the affected product across all versions prior to the fix.

RemediationAI

Vendor-released patch: 5.14.1 - upgrade the cphalcon extension to 5.14.1 or later, which replaces the short-circuiting identity comparison with a constant-time HMAC check (fix commit ad53ab1b2e7ec59b3af92b0b37b8aaa099011137 via PR https://github.com/phalcon/cphalcon/pull/17091, release https://github.com/phalcon/cphalcon/releases/tag/v5.14.1). Because this is a compiled PHP extension, rebuild/redeploy the extension and restart PHP-FPM/the web server after upgrading. If immediate upgrade is not possible, compensating controls include: avoid exposing decrypt() results or timing to untrusted callers (do not use Crypt to protect tamper-sensitive tokens sent to clients, such as cookies or signed state, until patched); add a random delay or perform verification of a full-length constant-time comparison in application wrapper code before calling decrypt (trade-off: adds latency and is imperfect); and rotate encryption keys after patching since forged content may have been accepted. Consult the advisory GHSA-8jqh-95g6-7jpj for authoritative guidance.