Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Soupsieve versions before 2.8.4 are vulnerable to regular expression denial of service through the CSS selector parser. An attacker who can supply a CSS selector string, such as an unterminated quoted attribute value, can make the parser consume CPU for seconds with a payload of about 300 bytes, which can block application threads. Upgrade to soupsieve 2.8.4 or later. No other workaround is listed.
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 |
|---|---|---|---|---|
| 7.5 | High | 3.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0064, the 51st percentile, on 15 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:11 UTC First seen by agentprime
- 31 Oct 2026, 14:11 UTC Confirmed by OSV