CVE-2026-49212
Symfony Ux 2.8.0 – 2.36.0
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/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:XCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-49212 is a medium-severity Insufficient Verification of Data Authenticity (CWE-345) vulnerability in Symfony Ux. Its CVSS base score is 6.9 (Medium).
Operationally, ranked at the 14th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-23 (Session Authenticity) and SI-7 (Software, Firmware, and Information Integrity) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-45209
Vulnerability Data
Symfony UX is a JavaScript ecosystem for Symfony. From 2.8.0 until 2.36.0 and 3.1.0, the HMAC computed by Symfony\UX\LiveComponent\LiveComponentHydrator covered only sorted prop key/value pairs and did not include the component name, the slot identifier (props vs propsFromParent), or request…
more
context, allowing a signed blob minted for one component or slot to be replayed in another and set a read-only prop on a target component. This issue is fixed in versions 2.36.0 and 3.1.0.
- CWE(s)
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Explicit requirement to protect session authenticity structurally prevents the weakness for communications.
Integrity verification tools detect (but do not stop) the acceptance of data lacking authenticity.
Cryptographic mechanisms can be used to verify authenticity, thereby preventing acceptance of invalid data.
Associating security attributes with exchanged information supports verification of authenticity.
Integrity protection on transmitted data directly stops acceptance of unauthenticated or altered data.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
A.8.24's guidance on identifying protection levels, selecting algorithms/strength for authenticity/integrity (items b,f), using cryptography for transmitted/stored data (c), and key management directly stops many CWE-345 exploits by ensuring verifiable authenticity; however, it leaves a bounded remainder where verification logic itself is flawed or absent (e.g. accepting unverified signatures or weak schemes), as the control depends on correct implementation in other mechanisms.
Secure SDLC incorporates authenticity verification requirements throughout development.
Application security requirements can mandate data authenticity verification mechanisms.
Secure coding practices include implementing proper data authenticity checks.
Security testing can detect missing or weak data authenticity verification.
Secure authentication of data sources ensures only valid, authentic data is accepted.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.