Summary
Package updates are available for Amazon Linux 2 that fix the following vulnerabilities: CVE-2026-42508: Previously, a revoked 'SignatureKey' belonging to a CA was not correctly checked for revocation. Now, both the 'key' and 'key.SignatureKey' are checked for @revoked. CVE-2026-39833: The in-memory keyring returned by NewKeyring() silently accepted keys with the ConfirmBeforeUse constraint but never enforced it. The key would sign without any confirmation prompt, with no indication to the caller that the constraint was not in effect. NewKeyring() now returns an error when unsupported constraints are requested. CVE-2026-39831: The Verify() method for FIDO/U2F security key types (sk-ecdsa-sha2-nistp256@openssh.com, sk-ssh-ed25519@openssh.com) did not check the User Presence flag. Signatures generated without physical touch were accepted, allowing unattended use of a hardware security key. To restore the previous behavior, return a "no-touch-required" extension in Permissions.Extensions from PublicKeyCallback. CVE-2026-39830: A malicious SSH peer could send unsolicited global request responses to fill an internal buffer, blocking the connection's read loop. The blocked goroutine could not be released by calling Close(), resulting in a resource leak per connection. Unsolicited global responses are now discarded. CVE-2026-39829: The RSA and DSA public key parsers did not enforce size limits on key parameters. A crafted public key with an excessively large modulus or DSA parameter could cause several minutes of CPU consumption during signature verification. This could be triggered by unauthenticated clients during public key authentication. RSA moduli are now limited to 8192 bits, and DSA parameters are validated per FIPS 186-2.
Fixed packages 2
| Release | Package | Fixed in |
|---|---|---|
| Amazon Linux · 2 | rclone | 0:1.55.1-1.amzn2.0.7 |
| Amazon Linux · 2 | rclone-debuginfo | 0:1.55.1-1.amzn2.0.7 |
Vulnerabilities 5
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Critical 9.1
Invoking client can cause server deadlock on unexpected responses in golang.org/x/crypto/ssh
A malicious SSH peer could send unsolicited global request responses to fill an internal buffer, blocking the connection's read loop. The blocked goroutine could not be released by calling Close(), resulting in a resource leak per connection. Unsolicited glob…
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Critical 9.1
Invoking bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh
The Verify() method for FIDO/U2F security key types (sk-ecdsa-sha2-nistp256@openssh.com, sk-ssh-ed25519@openssh.com) did not check the User Presence flag. Signatures generated without physical touch were accepted, allowing unattended use of a hardware securit…
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Critical 9.1
Invoking key constraints not enforced in golang.org/x/crypto/ssh/agent
The in-memory keyring returned by NewKeyring() silently accepted keys with the ConfirmBeforeUse constraint but never enforced it. The key would sign without any confirmation prompt, with no indication to the caller that the constraint was not in effect. NewKe…
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Critical 9.1
Invoking auth bypass via unenforced @revoked status in golang.org/x/crypto/ssh/knownhosts
Previously, a revoked 'SignatureKey' belonging to a CA was not correctly checked for revocation. Now, both the 'key' and 'key.SignatureKey' are checked for @revoked.
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High 7.5
Invoking pathological RSA/DSA parameters may cause DoS in golang.org/x/crypto/ssh
The RSA and DSA public key parsers did not enforce size limits on key parameters. A crafted public key with an excessively large modulus or DSA parameter could cause several minutes of CPU consumption during signature verification. This could be triggered by …
References
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web
https://alas.aws.amazon.com/cve/html/CVE-2026-39829.html
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web
https://alas.aws.amazon.com/cve/html/CVE-2026-39830.html
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web
https://alas.aws.amazon.com/cve/html/CVE-2026-39831.html
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web
https://alas.aws.amazon.com/cve/html/CVE-2026-39833.html
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web
https://alas.aws.amazon.com/cve/html/CVE-2026-42508.html