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Fencer Vulns
critical 9.8

CVE-2021-28940 json

Because of a incorrect escaped exec command in MagpieRSS in 0.72 in the /extlib/Snoopy.class.inc file, it is possible to add a extra comman…

published 2021-04-02 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-15591

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.3%
EPSS 3.3% chance of exploitation in 30 days, percentile 88%
public exploits
0
none known

Summary

Because of a incorrect escaped exec command in MagpieRSS in 0.72 in the /extlib/Snoopy.class.inc file, it is possible to add a extra command to the curl binary. This creates an issue on the /scripts/magpie_debug.php and /scripts/magpie_simple.php page that if you send a specific https url in the RSS URL field, you are able to execute arbitrary commands.

Exploit prediction

3.30% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • pastebin.com https://pastebin.com/kpzHKKJu referenced PoC, tagged "exploit" by a source, unverified
  • exploit-db.com https://www.exploit-db.com/exploits/49643 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Classification

Weakness
  • CWE-116 Improper Encoding or Escaping of Output

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.