---
title: "CVE-2015-1793\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2015-1793?format=md
keywords: index, follow
---

# CVE-2015-1793

Publication date 9 July 2015

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**6.5 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2015-1793?format=md#impact-score)

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## Description

The X509\_verify\_cert function in crypto/x509/x509\_vfy.c in OpenSSL 1.0.1n,
1.0.1o, 1.0.2b, and 1.0.2c does not properly process X.509 Basic
Constraints cA values during identification of alternative certificate
chains, which allows remote attackers to spoof a Certification Authority
role and trigger unintended certificate verifications via a valid leaf
certificate.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2015-1793?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| openssl | 15.04 vivid | Not affected |
| 14.10 utopic | Not affected |
| 14.04 LTS trusty | Not affected |
| 12.04 LTS precise | Not affected |
| openssl098 | 15.04 vivid | Not affected |
| 14.10 utopic | Not affected |
| 14.04 LTS trusty | Not in release |
| 12.04 LTS precise | Not affected |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

## Notes

---

### [mdeslaur](https://launchpad.net/~mdeslaur)

introduced by the following commit in 1.0.2b and 1.0.1n:
https://git.openssl.org/?p=openssl.git;a=commit;h=6281abc79623419eae6a64768c478272d5d3a426

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

6.5 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | Low |
  | Privileges required | None |
  | User interaction | None |
  | Scope | Unchanged |
  | Confidentiality impact | Low |
  | Integrity impact | Low |
  | Availability impact | None |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 6.5 · Medium |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-1793)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2015-1793)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2015-1793)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2015-1793)

### Other references

* <https://mta.openssl.org/pipermail/openssl-announce/2015-July/000037.html>
* <https://www.openssl.org/news/secadv_20150709.txt>
* <https://www.cve.org/CVERecord?id=CVE-2015-1793>