Summary
ux-live-component: Format-less date LiveProps parsed with the permissive DateTime constructor
Description
When a #[LiveProp] is typed as a DateTimeInterface and no explicit format is configured, Symfony\UX\LiveComponent\LiveComponentHydrator::hydrateObjectValue() falls back to new $className($value). The DateTime / DateTimeImmutable constructors accept relative strings such as "now", "tomorrow", or "+10 years", so a writable, format-less date prop can be pushed to an arbitrary point in time by the client. Components that rely on a date prop to gate time-based business logic can be moved past those checks by a frontend payload that no maintainer would consider a valid date.
Resolution
hydrateObjectValue() now parses format-less date props strictly with createFromFormat(DateTimeInterface::RFC3339, ...), matching the format already emitted by dehydrateObjectValue(). Normal round-trips are unaffected; only inputs that aren't valid RFC 3339 are now rejected, which is consistent with how a format-configured prop already behaved.
The patch for this issue is available here for branch 2.x (and forward-ported to 3.x).
Credits
Symfony would like to thank Pascal Cescon for reporting the issue and Hugo Alliaume for providing the fix.
Impact
The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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symfony/ux-live-component to 2.36.0 or later; symfony/ux-live-component to 3.1.0 or later
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Frequently Asked Questions
- What is CVE-2026-49208? CVE-2026-49208 is a medium-severity improper input validation vulnerability in symfony/ux-live-component (composer), affecting versions >= 2.8.0, < 2.36.0. It is fixed in 2.36.0, 3.1.0. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
- Which versions of symfony/ux-live-component are affected by CVE-2026-49208? symfony/ux-live-component (composer) versions >= 2.8.0, < 2.36.0 is affected.
- Is there a fix for CVE-2026-49208? Yes. CVE-2026-49208 is fixed in 2.36.0, 3.1.0. Upgrade to this version or later.
- Is CVE-2026-49208 exploitable, and should I be worried? Whether CVE-2026-49208 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-49208 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-49208?
- Upgrade
symfony/ux-live-componentto 2.36.0 or later - Upgrade
symfony/ux-live-componentto 3.1.0 or later
- Upgrade