Security readout for executives and security teams
Plain-English summary
CVE-2016-9586 is an older curl/libcurl buffer overflow tied to formatting very large floating-point output. Business risk is mainly service disruption, not data theft. Remote exposure depends on an application unsafely accepting an outside format string, so widespread internet-scale urgency is not supported by the provided sources.
Executive priority
Treat as a normal vulnerability management item unless affected systems are public-facing and expose attacker-controlled formatting paths. It warrants patch verification, not emergency response, based on the provided severity, KEV=false status, and high-complexity conditions.
Technical view
curl before 7.52.0 had a CWE-122 buffer overflow in libcurl's printf() implementation when handling large floating-point output. The CVSS vector rates network attack possible but high complexity, with availability impact only. The provided sources point to upstream correction and vendor updates from Red Hat, Debian LTS, and Gentoo.
Likely exposure
Likely exposure is systems running curl/libcurl before 7.52.0 or vendor-maintained packages missing the backported fix. Practical risk is higher where internal or public-facing applications allow attacker-influenced format strings to reach libcurl printf-style functionality.
Exploitation context
The bundle does not provide evidence of active exploitation, and KEV status is false. Remote attack is described as possible only where an application accepts a format string from outside without necessary filtering, which makes exploitation situational and high complexity.
Researcher notes
Key uncertainty is exploitability in a given application. The CVE describes the vulnerable primitive, but remote impact depends on unsafe application integration. Researchers should focus on version confirmation, vendor backport status, and whether untrusted format strings can reach the vulnerable libcurl formatting code.
Mitigation direction
- Upgrade curl/libcurl to 7.52.0 or a vendor-supported fixed package.
- Apply Red Hat, Debian LTS, Gentoo, or other vendor curl security updates where applicable.
- Find applications that pass external format strings into libcurl printf-style helpers.
- Remove, constrain, or validate externally supplied format strings in application code.
- Check vendor advisories when backported package versions differ from upstream curl versions.
Validation and detection
- Inventory curl and libcurl versions across servers, containers, and application images.
- Map installed vendor package versions to relevant vendor security advisories.
- Review code for user-controlled format strings reaching libcurl printf-style functions.
- Prioritize validation on network-facing services using libcurl.
- Confirm updated packages are deployed and old vulnerable builds are removed.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-122: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2016-9586 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.9 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H2.23.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
5.9MediumVector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- RHSA-2018:3558CVE reference · vendor-advisory, x_refsource_REDHAT
- [debian-lts-announce] 20181106 [SECURITY] [DLA 1568-1] curl security updateCVE reference · mailing-list, x_refsource_MLIST
- https://curl.haxx.se/docs/adv_20161221A.htmlCVE reference · x_refsource_CONFIRM
- https://github.com/curl/curl/commit/curl-7_51_0-162-g3ab3c16CVE reference · x_refsource_CONFIRM
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2016-9586CVE reference · x_refsource_MISC
- GLSA-201701-47CVE reference · vendor-advisory, x_refsource_GENTOO
- [bookkeeper-issues] 20210628 [GitHub] [bookkeeper] padma81 opened a new issue #2746: Security Vulnerabilities in CentOS 7 image, Upgrade image to CentOS 8CVE reference · mailing-list, x_refsource_MLIST
- [bookkeeper-issues] 20210629 [GitHub] [bookkeeper] padma81 opened a new issue #2746: Security Vulnerabilities in CentOS 7 image, Upgrade image to CentOS 8CVE reference · mailing-list, x_refsource_MLIST
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Heap-based Buffer Overflow
Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.