Sympa before 6.2.62 relies on a cookie parameter for certain security objectives, but does not ensure that this parameter exists and has an unpredictable value. Specifically, the cookie parameter is both a salt for stored passwords and an XSS protection mechanism.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-46900
• sympa-community/sympa#1091
• https://github.com/sympa-community/sympa-community.github.io/blob/master/security/2021-001.md
• https://www.sympa.community/security/2021-001.html