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CVE-2026-49212

MEDIUM 6.9

Published 2026-07-17 · Last modified 2026-07-17

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 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.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.2%chance of exploitation in 30 days · 6th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

6.9CVSS 4.0 · MEDIUM

  • ConfidentialityNone
  • IntegrityLow
  • AvailabilityNone

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable
  • ✓Requirements: No special attack requirements

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-49212/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-49212/poc.json

Affected

Vendors Symfony

Products Ux

Weakness (CWE)

  • CWE-345: : Insufficient Verification of Data Authenticity

CVSS 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

Known Affected Software Configurations

VendorProductVersion range
SymfonyUx≥ 2.8.0 and < 2.36.0
SymfonyUx3.0.0

All CVSS metrics

  • MEDIUM 6.9 v4.0 · CNA Primary
    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
  • MEDIUM 6.9 v4.0 · NVD Secondary
    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:X
  • HIGH 7.5 v3.1 · NVD Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References

Patches & mitigations

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS