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Fencer Intel
medium 4.8

CVE-2021-3271 json

Stored cross-site scripting in PressBooks

published 5y ago modified 4mo ago also GHSA-9652-78hp-w58c , EUVD-2021-0637

cvss
4.8
version 3.1, NVD
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

PressBooks 5.17.3 contains a cross-site scripting (XSS). Stored XSS can be submitted via the Book Info's Long Description Body, and all actions to open or preview the books page will result in the triggering the stored XSS.

Patch / fix

  • packagist pressbooks/pressbooks 5.18.0

Is CVE-2021-3271 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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Exploit prediction

0.94% chance of exploitation in the next 30 days, higher than 61% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/pressbooks/pressbooks/pull/2072 referenced PoC, tagged "exploit" by a source, unverified
  • gosecure.net https://www.gosecure.net/blog/2021/02/16/cve-2021-3271-pressbooks-stored-cross-site-scripting-proof-of-concept/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 4.8 CVSS:3.1/AV:N/AC:L/PR:H/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
GitHub 3.1 4.8 CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
packagist pressbooks/pressbooks
<5.18.0
5.18.0

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.