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Fencer Intel
medium 5.3

GHSA-f3cj-j4f6-wq85 json

Svelte: SSR XSS via Insecure Promise Serialization in hydratable

published 6mo ago modified 6mo ago

cvss
5.3
version 4.0, the maintainers
cisa kev
Not listed
not in CISA's catalog
epss
—
no score, EPSS covers CVEs only
public exploits
0
none known

Summary

Contents of `hydratable` promises were not properly stringified, potentially leading to an XSS exploit. You are vulnerable if all of the following is true: - you are using `hydratable` (an experimental feature at the time of this report) - you are passing attacker-controlled input such that a synchronous value is hydrated, then a promise value, e.g. `hydratable('someKey', () => [synchronousValue, promiseValue])`

Patch / fix

  • npm svelte 5.55.7

Is GHSA-f3cj-j4f6-wq85 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CVSS scores

assigned by version score vector
the maintainers 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

Affected packages

ecosystem package affected fixed in
npm svelte
>=5.46.0, <5.55.7
5.55.7

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of sveltejs/svelte published their own advisory on GitHub. Reviewed sources take precedence over it.