PatchTheCVECVE-2026-39827: An authenticated SSH client that repeatedly opened channels which were rejected by the server caused unbounded
CVE-2026-39827 is a medium-severity flaw (CVSS 6.5) affecting crypto. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
An authenticated SSH client that repeatedly opened channels which were rejected by the server caused unbounded memory growth, eventually crashing the server process and affecting all connected users. Rejected channels are now properly removed from the connection's internal state and released for garbage collection.
Why this priority
- No elevated risk signals yet
A fixed release or distro patch exists.
Risk facts
| CVSS score | 6.5 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | Low |
| User interaction | None |
| EPSS exploit chance | 0.3% (top 80%) |
| CISA exploited list | No |
| Weakness | CWE-924 |
| Published | 2026-05-22 |
| Last modified | 2026-07-23 |
Last updated 2026-07-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-39827?
crypto: upgrade to 0.52.0. Exact commands for each OS are on this page.
Is CVE-2026-39827 being exploited?
CVE-2026-39827 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-39827 affect?
CVE-2026-39827 affects crypto. Severity is medium (CVSS 6.5). An authenticated SSH client that repeatedly opened channels which were rejected by the server caused unbounded memory growth, eventually crashing the server process and affecting all connected users. Rejected channels are now properly remov
How urgent is CVE-2026-39827?
Priority 28/100. No elevated risk signals yet.
Software pages
Related CVEs
- CVE-2026-39835 MEDIUM 5.3 UPGRADE SSH servers which use CertChecker as a public key callback without setting IsUserAuthority or IsHostAuthority
- CVE-2026-39830 CRITICAL 9.1 UPGRADE A malicious SSH peer could send unsolicited global request responses to fill an internal buffer, blocking the
- CVE-2026-39829 HIGH 7.5 UPGRADE The RSA and DSA public key parsers did not enforce size limits on key parameters
- CVE-2026-42508 CRITICAL 9.1 UPGRADE Previously, a revoked 'SignatureKey' belonging to a CA was not correctly checked for revocation
- CVE-2026-39832 CRITICAL 9.1 UPGRADE When adding a key to a remote agent constraint extensions such as restrict-destination-v00@openssh.com were no