CVE intelligence and bounded remediation
CVE-2026-39832 — When adding a key to a remote agent constraint extensions such as restrict-destination-v00@openssh.com were not serialized in the request
When adding a key to a remote agent constraint extensions such as restrict-destination-v00@openssh.com were not serialized in the request. Destination restrictions were silently stripped when forwarding keys, allowing unrestricted use of the key on the remote host. The client now serializes all constraint extensions. Additionally, the in-memory keyring returned by NewKeyring() now rejects keys with unsupported constraint extensions instead of silently ignoring them.
- Severity
- Critical
- CVSS
- 9.1 (3.1)
- Published
- 2026-05-22
- CISA KEV
- Not currently listed
- Ecosystem
- software/application
- Weaknesses
- CWE-502, CWE-281
Affected products
- golang / crypto
Matched remediation archetype
Unsafe deserialization and object reconstruction
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
Check exposure
- Inventory serialization formats accepted from requests, queues, caches, files, cookies, and cross-service messages.
- Trace whether untrusted input can select classes, types, callbacks, constructors, or object hooks during decoding.
- Identify signing, schema validation, trust-boundary, and compatibility settings for each decoder.
Remediate safely
- Replace native object deserialization with a data-only format and explicit schema validation.
- If replacement is not immediate, use a safe decoder with a minimal type allowlist and disable polymorphic or executable hooks.
- Update the affected library and add inert tests for unknown types, extra fields, malformed nesting, and unsigned data.
Authoritative sources
Complete CVE record and remediation plan
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