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CVE-2026-97031

Reject malformed ECH outer extension references in crypto/tls

No known exploitation. EPSS puts it in the 32nd percentile. Fixed versions are out.

CVSS 3.17.5HighEPSS percentile32nd0.4% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
No public exploit knownFix1 product2 fixed builds listed below

Published Updated Sources: CVE.org, NVD

NVD CVE.org

What to do

Find your product and version, then upgrade to the build on the right.

  • Go standard library crypto/tlsAffected: < 1.26.9Upgrade to: 1.26.9Affected: ≥ 1.27.0-0, < 1.27.2Upgrade to: 1.27.2Stated by: CVE record

Versions as the sources state them. Full version matrix after sign-in

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What it is

From the CVE record

Multiple ECH outer extension references are not permitted under RFC 9849; previously, a client could send a well-crafted packet that could trigger memory exhaustion in the server process by specifying multiple references. We now reject these as malformed and curb the memory amplification vector as a result.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS32nd
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

0.4% chance of exploitation activity in the next 30 days, which ranks it in the 32nd percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

4 events over 1 day, from the signal feeds we watch.

  1. Record updated
  2. Publishedweakness classified, record updated

Affected products

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Scored 7.5 by NVD.

How it is reached

  • Attack Vector NetworkExploitable remotely over the network without any special conditions
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required NoneNo authentication required — anyone can exploit this
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

  • Confidentiality NoneNo confidentiality impact
  • Integrity NoneNo integrity impact
  • Availability HighTotal denial of service — the component is completely unavailable

Weaknesses

Sources

References in the record

And 1 more reference. See all after sign-in

In the news

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We'll flag the next CVE, public exploit or patch for Crypto/tls, not every advisory.