# CVE-2019-1559: libssl1.0.0: If an application encounters a fatal protocol error and then calls SSL_shutdown() twice (once to send a close_notify,...

CVE-2019-1559 is fixed in 2 products on 1 platform, first by libssl1.0.0 1.0.2n-1ubuntu5.3, released February 25, 2019. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2019-1559
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.1714
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 25, 2019

## Description

If an application encounters a fatal protocol error and then calls SSL_shutdown() twice (once to send a close_notify, and once to receive one) then OpenSSL can respond differently to the calling application if a 0 byte record is received with invalid padding compared to if a 0 byte record is received with an invalid MAC. If the application then behaves differently based on that in a way that is detectable to the remote peer, then this amounts to a padding oracle that could be used to decrypt data. In order for this to be exploitable "non-stitched" ciphersuites must be in use. Stitched ciphersuites are optimised implementations of certain commonly used ciphersuites. Also the application must call SSL_shutdown() twice even if a protocol error has occurred (applications should not do this but some do anyway). Fixed in OpenSSL 1.0.2r (Affected 1.0.2-1.0.2q).

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libssl1.0.0 Ubuntu 18.04.6 LTS (bionic) | 1.0.2n-1ubuntu5.3 | [libssl1.0.0 1.0.2n-1ubuntu5.3](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libssl1.0.0-1.0.2n-1ubuntu5.3.md) | Feb 25, 2019 |
| Linux | openssl1.0 Ubuntu 18.04.6 LTS (bionic) | 1.0.2n-1ubuntu5.3 | [openssl1.0 1.0.2n-1ubuntu5.3](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-openssl1.0-1.0.2n-1ubuntu5.3.md) | Feb 25, 2019 |

---

Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.