Security readout for executives and security teams
Plain-English summary
json-c, a common JSON parsing library, had an integer overflow that could lead to memory corruption when processing a very large JSON file. Business risk is highest where software parses untrusted JSON. The CVE is high severity, but the supplied sources do not show active exploitation.
Executive priority
Treat as a high-priority patching issue for systems that parse untrusted JSON. It is not currently supported by KEV evidence of active exploitation, so prioritize based on exposure and vendor update availability.
Technical view
CVE-2020-12762 affects json-c through 0.14. The flaw is an integer overflow and out-of-bounds write in printbuf_memappend, classified as CWE-787. CVSS 3.1 is 7.8 with local attack vector and required user interaction. Multiple Linux distributions issued security updates.
Likely exposure
Exposure is likely through operating system packages, embedded products, containers, or applications linking json-c through 0.14. Prioritize systems that parse user-supplied, uploaded, imported, or otherwise untrusted JSON files. The provided affected CPE data is incomplete.
Exploitation context
The supplied CVSS vector requires local access and user interaction. KEV status is false, and the provided sources do not establish active exploitation. The public description confirms a large JSON file can trigger the memory corruption condition.
Researcher notes
The strongest evidence is the CVE description, upstream json-c pull request reference, and multiple distribution advisories. Affected product metadata is sparse, so validation should rely on package inventories, SBOMs, and vendor advisories rather than CPE matching alone.
Mitigation direction
- Inventory json-c packages and bundled copies across hosts, containers, and appliances.
- Apply vendor security updates from Linux distributions or upstream json-c guidance.
- Prioritize systems that process untrusted or externally supplied JSON files.
- Review downstream product advisories for appliances or embedded software using json-c.
- If no update exists, restrict untrusted large JSON processing until vendor guidance is available.
Validation and detection
- Check package managers and SBOMs for json-c versions through 0.14.
- Confirm installed vendor packages include the CVE-2020-12762 security fix.
- Identify applications that parse uploaded, imported, or user-controlled JSON files.
- Review scanner results against Ubuntu, Debian, Fedora, and Gentoo advisories.
- Document any bundled json-c copies not covered by OS package updates.
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-787: 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-2020-12762 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
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/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:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H1.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/json-c/json-c/pull/592CVE reference
- https://github.com/rsyslog/libfastjson/issues/161CVE reference
- FEDORA-2020-63c6f4ab1dCVE reference · vendor-advisory
- USN-4360-1CVE reference · vendor-advisory
- FEDORA-2020-847ad856abCVE reference · vendor-advisory
- FEDORA-2020-7eb7eac270CVE reference · vendor-advisory
- [debian-lts-announce] 20200531 [SECURITY] [DLA 2228-1] json-c security updateCVE reference · mailing-list
- [debian-lts-announce] 20200531 [SECURITY] [DLA 2228-2] json-c regression updateCVE reference · mailing-list
- USN-4360-4CVE reference · vendor-advisory
- GLSA-202006-13CVE reference · vendor-advisory
- [debian-lts-announce] 20200730 [SECURITY] [DLA 2301-1] json-c security updateCVE reference · mailing-list
- DSA-4741CVE reference · vendor-advisory
- https://security.netapp.com/advisory/ntap-20210521-0001/CVE reference
- https://cert-portal.siemens.com/productcert/pdf/ssa-637483.pdfCVE reference
- [debian-lts-announce] 20230620 [SECURITY] [DLA 3461-1] libfastjson security updateCVE reference · mailing-list
- https://lists.debian.org/debian-lts-announce/2025/07/msg00021.htmlCVE reference
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.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.