Skip to content
Fencer Vulns
medium 6.5

CVE-2020-5290 json

session fixation in rCTF

published 2020-04-01 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-26484

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

In RedpwnCTF before version 2.3, there is a session fixation vulnerability in exploitable through the `#token=$ssid` hash when making a request to the `/verify` endpoint. An attacker team could potentially steal flags by, for example, exploiting a stored XSS payload in a CTF challenge so that victim teams who solve the challenge are unknowingly (and against their will) signed into the attacker team's account. Then, the attacker can gain points / value off the backs of the victims. This is patched in version 2.3.

Patch / fix

  • ctfd rctf 2.3

Exploit prediction

0.82% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/redpwn/rctf/security/advisories/GHSA-p5fh-2vhw-fvpq referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/redpwn/rctf/issues/147 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:H/A:N
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

  • redpwn rctf

Classification

Weakness

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.