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Vulnerabilities

Vulnerability · CVE-2026-56862

Limit handshake messages we are willing to accept post-handshake in crypto/tls

Published Aug 13, 2026 · catalog updated Oct 15, 2026 · Limit handshake messages we

Check if you run it

No confirmed exploitation is on record for CVE-2026-56862. EPSS is 0.57%. Act only if a listed version of Limit handshake messages we is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Limit handshake messages we).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Unknown—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.57%
Remediation
Not established
Affected products
Go stdlib

Handshake messages, such as KeyUpdate, are always considered as state-advancing, regardless of whether a handshake has been completed or not. As a result, a malicious client can keep sending KeyUpdate messages to force the server to keep performing key derivation operations indefinitely.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Go stdlib0 → 1.25.13

How to fix CVE-2026-56862

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-56862. EPSS is 0.57%. Act only if a listed version of Limit handshake messages we is installed.

Which versions are affected?

Compare what you have installed with 0 → 1.25.13. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.57%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Aug 13, 2026 · Catalog

    Detected

    Handshake messages, such as KeyUpdate, are always considered as state-advancing, regardless of whether a handshake has been completed or not. As a result, a malicious client can keep sending KeyUpdate messages to force the server to keep performing key derivation operations indefinitely.

  2. Oct 10, 2026 · Catalog

    Fix available

    Go stdlib 0 → 1.25.13

  3. Oct 10, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    stdlib fixed in 1.25.13

  4. Oct 10, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    stdlib fixed in 1.25.13

  5. Oct 10, 2026 · Catalog

    Updated

    Handshake messages, such as KeyUpdate, are always considered as state-advancing, regardless of whether a handshake has been completed or not. As a result, a malicious client can keep sending KeyUpdate messages to force the server to keep performing key derivation operations indefinitely.

  6. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    Handshake messages, such as KeyUpdate, are always considered as state-advancing, regardless of whether a handshake has been completed or not. As a result, a malicious client can keep sending KeyUpdate messages to force the server to keep performing key derivation operations indefinitely.

Sources

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.