Is CVE-2026-97031 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-97031 being exploited in the wild.

How severe is CVE-2026-97031?

High severity, with a CVSS score of 7.5, published 8 October 2026.

Which products and versions are affected?

go (Go) ; stdlib (Go) SEMVER:introduced=0,fixed=1.26.9,introduced=1.27.0-0,fixed=1.27.2.

Is there a fix for CVE-2026-97031?

Yes. stdlib (Go): upgrade to 1.27.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-97031 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-97031?

Check whether you run go (Go) or stdlib (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-97031: Go crypto/tls malformed ECH extension DoS

CVE-2026-97031 · Severity: high · CVSS 7.5 · Published 2026-10-08

Go's crypto/tls library, which handles encrypted client hello (ECH) negotiation in TLS connections, accepts malformed extension references that violate the ECH specification. An attacker can send a crafted packet with multiple ECH outer extension references to trigger memory exhaustion in the server, causing a denial of service.

Technologies: go (Go), stdlib (Go). Vendors: Go.

Quick answers

Is CVE-2026-97031 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-97031 being exploited in the wild.
How severe is CVE-2026-97031?: High severity, with a CVSS score of 7.5, published 8 October 2026.
Which products and versions are affected?: go (Go) <UNKNOWN>; stdlib (Go) SEMVER:introduced=0,fixed=1.26.9,introduced=1.27.0-0,fixed=1.27.2.
Is there a fix for CVE-2026-97031?: Yes. stdlib (Go): upgrade to 1.27.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-97031 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-97031?: Check whether you run go (Go) or stdlib (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

stdlib (Go): upgrade to 1.27.2 or later
```
go get stdlib@v1.27.2
```

Technical details

The vulnerability is a denial-of-service issue in Go's crypto/tls ECH handling where multiple ECH outer extension references—which are not permitted under RFC 9849—are not rejected, allowing a remote attacker to exhaust server memory through a memory amplification vector. The fix rejects malformed ECH packets with multiple extension references as invalid.

Affected products

Go Go <UNKNOWN>

Identifiers

CVE-2026-97031
GO-2026-6607

Timeline

2026-10-08: disclosed

References

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