Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Packagist package yeswiki/yeswiki versions from 4.6.2 before 4.6.6 are affected. The ActivityPub inbox signature check in HttpSignatureService uses a negated openssl_verify() result, so a verification error returning -1 is treated as success. An unauthenticated attacker can send Create, Update, or Delete activities to an ActivityPub-enabled form's inbox and have them processed, altering or deleting bazar entries. Upgrade to version 4.6.6.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 8.2 | High | 3.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0035, the 29th percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:25 UTC First seen by agentprime
- 31 Oct 2026, 14:25 UTC Confirmed by OSV