CVE-2019-15522Network attack vector

Unauthenticated SSL bypass via accepted plaintext HELLO

Published Mar 20, 2020 · Updated Aug 5, 2024

SSL enforcement bypass in LINBIT csync2 2.0 and earlier allows remote attackers to continue a HELLO session without required SSL. When csync_daemon_session receives a plaintext HELLO while SSL is required, it sends an SSL-expected error but leaves the peer set, so command processing continues. Network access to the daemon and an SSL-required configuration are necessary; pre-shared-key authentication still governs file synchronization.

CVSS severity9.8
Critical
EPSS probability1.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

SSL enforcement bypass in LINBIT csync2 2.0 and earlier allows remote attackers to continue a HELLO session without required SSL. When csync_daemon_session receives a plaintext HELLO while SSL is required, it sends an SSL-expected error but leaves the peer set, so command processing continues. Network access to the daemon and an SSL-required configuration are necessary; pre-shared-key authentication still governs file synchronization.

The record

CVE
CVE-2019-15522
Published
Mar 20, 2020
Updated
Aug 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 20, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo