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Fencer Vulns
medium 4.3

CVE-2026-3990 json

CesiumGS CesiumJS standalone.html cross site scripting

published 2026-03-12 7 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-11534

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 24%
public exploits
0
none known

Summary

A security flaw has been discovered in CesiumGS CesiumJS up to 1.137.0. Affected by this issue is some unknown functionality of the file Apps/Sandcastle/standalone.html. The manipulation of the argument c results in cross site scripting. The attack can be launched remotely. The exploit has been released to the public and may be used for attacks. The presence of this vulnerability remains uncertain at this time. The vendor was contacted early about this disclosure but did not respond in any way. According to CVE-2023-48094, "the vendor's position is that Apps/Sandcastle/standalone.html is part of the CesiumGS/cesium GitHub repository, but is demo code that is not part of the CesiumJS JavaScript library product."

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
7 mo ago

Exploit prediction

0.31% chance of exploitation in the next 30 days, higher than 24% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/AnalogyC0de/public_exp/issues/18 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N/E:P/RL:X/RC:R
CNA 3.0 4.3 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N/E:P/RL:X/RC:R
CNA 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N/E:POC/RL:ND/RC:UR
CNA 4.0 2.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/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
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
CNA 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N

Affected products

  • CesiumGS CesiumJS

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation
  • CWE-94 Improper Control of Generation of Code

References

Sources

Fencer Vulns 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.