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Fencer Vulns
medium 5.4

CVE-2021-21365 json

Cross-Site Scripting in Content Rendering

published 2021-04-27 5 y ago modified 2026-07-08 4 mo ago also BIT-typo3-2021-21365 , EUVD-2021-0849 , GHSA-p48w-vf3c-rqjx

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 61%
public exploits
0
none known

Summary

Bootstrap Package is a theme for TYPO3. It has been discovered that rendering content in the website frontend is vulnerable to cross-site scripting. A valid backend user account is needed to exploit this vulnerability. Users of the extension, who have overwritten the affected templates with custom code must manually apply the security fix. Update to version 7.1.2, 8.0.8, 9.1.4, 10.0.10 or 11.0.3 of the Bootstrap Package that fix the problem described. Updated version are available from the TYPO3 extension manager, Packagist and at https://extensions.typo3.org/extension/download/bootstrap_package/.

Patch / fix

  • packagist bk2k/bootstrap-package 7.1.2, 8.0.8, 9.0.4, 9.1.3, 10.0.10, 11.0.3
  • bitnami typo3 7.1.2, 8.0.8, 9.0.4, 9.1.3, 10.0.10, 11.0.3
  • typo3 typo3 7.1.2, 8.0.8, 9.0.4, 9.1.3, 10.0.10, 11.0.3

Exploit prediction

0.94% chance of exploitation in the next 30 days, higher than 61% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • typo3.org https://typo3.org/security/advisory/typo3-ext-sa-2021-007 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/benjaminkott/bootstrap_package/security/advisories/GHSA-p48w-vf3c-rqjx referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
GitHub 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 3.5 AV:N/AC:M/Au:S/C:N/I:P/A:N
OSV 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
packagist bk2k/bootstrap-package
>=7.1.0, <7.1.2
>=8.0.0, <8.0.8
>=9.0.0, <9.0.4
>=9.1.0, <9.1.3
>=10.0.0, <10.0.10
>=11.0.0, <11.0.3
7.1.2
8.0.8
9.0.4
9.1.3
10.0.10
11.0.3
bitnami typo3
<7.1.2
>=8.0.0, <8.0.8
>=9.0.0, <9.0.4
>=9.1.0, <9.1.3
>=10.0.0, <10.0.10
>=11.0.0, <11.0.3
7.1.2
8.0.8
9.0.4
9.1.3
10.0.10
11.0.3

Affected products

  • benjaminkott bootstrap_package

Classification

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

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.