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CVE-2026-56855 (GCVE-0-2026-56855)

Vulnerability from cvelistv5 – Published: 2026-09-02 19:37 – Updated: 2026-09-03 14:14
VLAI
Title
Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh
Summary
Previously, after a channel has been established, a malicious peer could send crafted messages that would deadlock the entire connection. Now, we handle all RFC 4254 channel messages; global requests are handled explicitly. Then, treat all other messages as a protocol error and tear the connection down instead of buffering and blocking.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-03 14:13 UTC
CWE
  • CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
Impacted products
Vendor Product Version CPE status
golang.org/x/crypto golang.org/x/crypto/ssh Affected: 0 , < 0.56.0 (semver)
guessed Create a notification for this product.
Credits
Will Mortensen
Show details on NVD website
To clipboard 

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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.