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Fencer Vulns
high 7.3

CVE-2022-21169 json

Prototype Pollution

published 2022-09-26 4 y ago modified 2026-06-17 4 mo ago also GHSA-grjp-4jmr-mjcw , EUVD-2022-6830

cvss
7.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 61%
public exploits
0
none known

Summary

The package express-xss-sanitizer before 1.1.3 are vulnerable to Prototype Pollution via the allowedTags attribute, allowing the attacker to bypass xss sanitization.

Patch / fix

  • npm express-xss-sanitizer 1.1.3
  • n/a express-xss-sanitizer 1.1.3

CISA SSVC

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

Exploit prediction

0.95% chance of exploitation in the next 30 days, higher than 61% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • security.snyk.io https://security.snyk.io/vuln/SNYK-JS-EXPRESSXSSSANITIZER-3027443 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/AhmedAdelFahim/express-xss-sanitizer/issues/4 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P
CNA 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
GitHub 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm express-xss-sanitizer
<1.1.3
1.1.3

Affected products

  • n/a express-xss-sanitizer

Classification

Weakness
  • CWE-1321 Improperly Controlled Modification of Object Prototype Attributes

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.