RabbitMQ: Plaintext username:password stored in an insecure cookie after successful POST /login

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

RabbitMQ is a messaging and streaming broker. From 4.2.0 until 4.2.8 and 4.3.2, a successful POST /login caused is_authorized/2 to set an auth cookie containing base64-encoded username:password credentials without HttpOnly, Secure, SameSite, or expiration protections. Because base64 is encoding rather than encryption, an attacker with same-origin cross-site scripting, an HTTP-readable network position, or local access to the browser cookie store could recover the actual login credentials; older browsers that treated an absent SameSite attribute as None also sent the cookie cross-site. This issue is fixed in versions 4.2.8 and 4.3.2.

Source published

25 Sep 2026 15:59:10 UTC

Source modified

28 Sep 2026 13:41:39 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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CVSS 4.0 · 8.2 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N