Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Deno versions 2.0.0 through 2.7.7 (crates.io package deno) are affected. When autoSelectFamily is enabled, which is the default, and the first address-family connection attempt fails, a TLS client using the node:tls or node:https APIs can send data written before the secureConnect event in plaintext. A network attacker who can make the initial connection attempt fail, such as by dropping IPv6 traffic, can then read or modify that data. Upgrade to Deno 2.7.8 or later.
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 |
|---|---|---|---|---|
| 7.4 | High | 3.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0023, the 14th percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 15:18 UTC First seen by agentprime
- 31 Oct 2026, 15:18 UTC Confirmed by OSV