CVE-2016-6309
Criticalstatem/statem.c in OpenSSL 1.1.0a does not consider memory-block movement after a realloc call, which allows remote attackers to cause a denial of service (use-after-free) or possibly execute arbitrary code via a crafted TLS session.
Published Sep 26, 2016 · Updated Jul 8, 2026
Key Facts
Patch immediately- CVE-2016-6309 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Openssl.
- It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
- EPSS estimates a 70% probability of exploitation in the next 30 days.
- Fixed versions are available, including Openssl 0.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
9.8
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
70%
Higher than 99.3% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
None known
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Description
statem/statem.c in OpenSSL 1.1.0a does not consider memory-block movement after a realloc call, which allows remote attackers to cause a denial of service (use-after-free) or possibly execute arbitrary code via a crafted TLS session.
Affected Products
6 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| OpensslOpenssl | 1.1.0a | 0 |
Timeline
Publicly disclosed
Sep 26, 2016
Last updated
Jul 8, 2026
Weakness Type
- CWE-416 Use After Free
References
- advisoryhttps://www.openssl.org/news/secadv/20160926.txt
- otherhttp://kb.juniper.net/InfoCenter/index?page=content&id=JSA10759
- otherhttps://bto.bluecoat.com/security-advisory/sa132
- otherhttps://git.openssl.org/?p=openssl.git%3Ba=commit%3Bh=acacbfa7565c78d2273c0b2a2e5e803f44afefeb
- otherhttps://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf03856en_us
FAQ
Common Questions.
statem/statem.c in OpenSSL 1.1.0a does not consider memory-block movement after a realloc call, which allows remote attackers to cause a denial of service (use-after-free) or possibly execute arbitrary code via a crafted TLS session.
Affected: Openssl versions 1.1.0a. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Openssl 0.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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