CVE-2020-12762 json
json-c through 0.14 has an integer overflow and out-of-bounds write via a large JSON file, as demonstrated by printbuf_memappend.
published 6y ago modified 26d ago also EUVD-2020-5047
- cvss
- 7.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.9%
- EPSS 1.9% chance of exploitation in 30 days, percentile 79%
- public exploits
- 0
- none known
Summary
json-c through 0.14 has an integer overflow and out-of-bounds write via a large JSON file, as demonstrated by printbuf_memappend.
Patch / fix
- Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
- Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
- Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem V1.1
- Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
- Siemens RUGGEDCOM ROX MX5000 V2.17.0
- Siemens RUGGEDCOM ROX MX5000RE V2.17.0
- Siemens RUGGEDCOM ROX RX1400 V2.17.0
- Siemens RUGGEDCOM ROX RX1500 V2.17.0
- Siemens RUGGEDCOM ROX RX1501 V2.17.0
- Siemens RUGGEDCOM ROX RX1510 V2.17.0
- Siemens RUGGEDCOM ROX RX1511 V2.17.0
- Siemens RUGGEDCOM ROX RX1512 V2.17.0
- Siemens RUGGEDCOM ROX RX1524 V2.17.0
- Siemens RUGGEDCOM ROX RX1536 V2.17.0
- Siemens RUGGEDCOM ROX RX5000 V2.17.0
- json-c Debian 14, Debian 13, Debian 12 0.13.1+dfsg-8
- libfastjson Debian 14, Debian 13, Debian 12 1.2304.0-1
debian advisories DEBIAN-CVE-2020-12762
- json-c Ubuntu 16.04 LTS 0.11-4ubuntu2.6
- json-c Ubuntu 18.04 LTS 0.12.1-1.3ubuntu0.3
- json-c Ubuntu 20.04 LTS 0.13.1+dfsg-7ubuntu0.3
- json-c Ubuntu Pro 14.04 LTS 0.11-3ubuntu1.2+esm3
ubuntu advisories UBUNTU-CVE-2020-12762
Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0
- libfastjson RHEL 8 0.99.9-2.el8
- libfastjson RHEL 9 0.99.9-5.el9
- json-c RHEL 8 0.13.1-2.el8
- libfastjson RHEL 9.0 EUS 0.99.9-3.el9_0.1
- libfastjson RHEL 9.2 EUS 0.99.9-3.el9_2.1
- libfastjson RHEL 8.8 EUS 0.99.9-1.el8_8.1
- libfastjson RHEL 8.6 EUS 0.99.9-1.el8_6.1
red hat advisories RHSA-2024:1154RHSA-2024:1086RHSA-2024:0573RHSA-2024:0411RHSA-2023:6976RHSA-2023:6431
- libfastjson SLES for SAP 12 SP5, SLES 12 SP5 0.99.8-3.6.1
- libfastjson SLES for SAP 15 SP3, SLES for SAP 15 SP2, SLES 15 SP3-LTSS +4 more 0.99.8-150000.3.3.1
- libfastjson SLE Module for Basesystem 15 SP4, openSUSE Leap 15.4 0.99.9-150400.3.3.1
- json-c SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES 12 SP5 +6 more 0.12.1-4.3.1
- json-c SLES 15 SP2-BCL, SLES 15 SP1-BCL, SLE Real Time 15 SP2 +20 more 0.13-3.3.1
suse advisories SUSE-SU-2024:1846-1SUSE-SU-2024:1775-1SUSE-SU-2023:2135-1SUSE-SU-2022:3001-1SUSE-SU-2022:0184-2SUSE-SU-2022:0184-1
- json-c openSUSE Leap 15.3 0.13-3.3.1
opensuse advisories openSUSE-SU-2022:0184-1
- libfastjson AlmaLinux 8 0.99.9-2.el8
- libfastjson AlmaLinux 9 0.99.9-5.el9
almalinux advisories ALSA-2023:6976ALSA-2023:6431
- libfastjson Rocky Linux 8 0.99.9-2.el8
- libfastjson Rocky Linux 9 0.99.9-5.el9
- json-c Rocky Linux 8 0.13.1-2.el8
rocky linux advisories RLSA-2023:6976RLSA-2023:6431RLSA-2021:4382
- json-c Alpine 3.11, Alpine 3.10, Alpine 3.9 0.13.1-r1
- json-c Alpine 3.24, Alpine 3.23, Alpine 3.22 +10 more 0.14-r1
- libfastjson Alpine 3.24, Alpine 3.23, Alpine 3.22 +7 more 1.2304.0-r0
alpine advisories ALPINE-CVE-2020-12762
Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0
- json-c CBL-Mariner 2.0 0.15-2
azure linux advisories AZL-6506
Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT
- json-c Arch Linux 0.15-1
arch linux advisories AVG-1160
- github.com/json-c/json-c#592 pull request
Is CVE-2020-12762 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerVendor advisories
What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
red hat product security vex CVE-2020-12762 updated cvss 7.8
libfastjson: integer overflow and out-of-bounds write via a large JSON file
-
Red Hat Enterprise Linux 6 json-c Red Hat Enterprise Linux 7 json-caffected: workaround, no fix planned “Will not fix”
-
Red Hat CodeReady Linux Builder (v. 8) json-c-doc 0.13.1-2.el8fixed: vendor fix RHSA-2021:4382
-
Red Hat CodeReady Linux Builder (v. 9) libfastjson-devel 0.99.9-5.el9, libfastjson-debuginfo 0.99.9-5.el9, libfastjson-debugsource 0.99.9-5.el9fixed: vendor fix RHSA-2023:6431
-
Red Hat Enterprise Linux AppStream (v. 8) libfastjson 0.99.9-2.el8fixed: vendor fix RHSA-2021:4382
-
Red Hat Enterprise Linux AppStream (v. 9) libfastjson 0.99.9-5.el9fixed: vendor fix RHSA-2023:6431
-
Red Hat Enterprise Linux AppStream EUS (v.8.6) libfastjson 0.99.9-1.el8_6.1fixed: vendor fix RHSA-2024:0411
-
Red Hat Enterprise Linux AppStream EUS (v.8.8) libfastjson 0.99.9-1.el8_8.1fixed: vendor fix RHSA-2024:0573
-
Red Hat Enterprise Linux AppStream EUS (v.9.0) libfastjson 0.99.9-3.el9_0.1fixed: vendor fix RHSA-2024:1154
show 3 moreshow fewer
-
Red Hat Enterprise Linux AppStream EUS (v.9.2) libfastjson 0.99.9-3.el9_2.1fixed: vendor fix RHSA-2024:1086
-
Red Hat Enterprise Linux BaseOS (v. 8) json-c 0.13.1-2.el8fixed: vendor fix RHSA-2021:4382
-
Red Hat Enterprise Linux 9 json-cnot affected: vulnerable code not present
Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf
cisa ICSA-23-348-10 updated cvss 7.8
Siemens SIMATIC S7-1500
-
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5affected: fixed in V3.1.5, mitigation support.industry.siemens.com
Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf
cisa ICSA-23-166-11 updated cvss 7.8
Siemens SIMATIC S7-1500 TM MFP Linux Kernel
-
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem <V1.1affected: fixed in V1.1, workaround support.industry.siemens.com
Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf
cisa ICSA-22-258-05 updated cvss 7.8
Siemens SINEC INS
-
Siemens SINEC INS <V1.0_SP2affected: fixed in V1.0 support.industry.siemens.com
Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- last yr.
Exploit prediction
1.90% chance of exploitation in the next 30 days, higher than 79% of all scored CVEs (FIRST EPSS, 2026-11-09).
Exploits and checks
- github.com https://github.com/json-c/json-c/pull/592 referenced PoC, tagged "exploit" by a source, unverified
- github.com https://github.com/rsyslog/libfastjson/issues/161 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| NVD | 3.1 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| CNA | 3.1 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| NVD | 2.0 | 6.8 | AV:N/AC:M/Au:N/C:P/I:P/A:P |
Affected products
- Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
- Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
- Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
- Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
- Siemens RUGGEDCOM ROX MX5000
- Siemens RUGGEDCOM ROX MX5000RE
- Siemens RUGGEDCOM ROX RX1400
- Siemens RUGGEDCOM ROX RX1500
- Siemens RUGGEDCOM ROX RX1501
- Siemens RUGGEDCOM ROX RX1510
- Siemens RUGGEDCOM ROX RX1511
- Siemens RUGGEDCOM ROX RX1512
- Siemens RUGGEDCOM ROX RX1524
- Siemens RUGGEDCOM ROX RX1536
- Siemens RUGGEDCOM ROX RX5000
Classification
References
-
github.com
/json-c/json-c/pull/592
exploit, patch, third-party-advisory
-
github.com
/rsyslog/libfastjson/issues/161
exploit, third-party-advisory
-
lists.fedoraproject.org
/archives/list/package-announce%40lists.fedoraproject.org/message/CQQRRGBQCAWNCCJ2HN3W5SSCZ4QGMXQI/
vendor-advisory
-
usn.ubuntu.com
/4360-1/
vendor-advisory, third-party-advisory
-
lists.fedoraproject.org
/archives/list/package-announce%40lists.fedoraproject.org/message/CBR36IXYBHITAZFB5PFBJTED22WO5ONB/
vendor-advisory
-
lists.fedoraproject.org
/archives/list/package-announce%40lists.fedoraproject.org/message/W226TSCJBEOXDUFVKNWNH7ETG7AR6MCS/
vendor-advisory
-
usn.ubuntu.com
/4360-4/
vendor-advisory, third-party-advisory
-
security.gentoo.org
/glsa/202006-13
vendor-advisory, third-party-advisory
-
debian.org
/security/2020/dsa-4741
vendor-advisory, third-party-advisory
-
lists.debian.org
/debian-lts-announce/2020/05/msg00032.html
mailing-list, third-party-advisory
-
lists.debian.org
/debian-lts-announce/2020/05/msg00034.html
mailing-list, third-party-advisory
-
lists.debian.org
/debian-lts-announce/2020/07/msg00031.html
mailing-list, third-party-advisory
-
security.netapp.com
/advisory/ntap-20210521-0001/
third-party-advisory
-
cert-portal.siemens.com
/productcert/pdf/ssa-637483.pdf
third-party-advisory
-
lists.debian.org
/debian-lts-announce/2023/06/msg00023.html
mailing-list, third-party-advisory
- lists.debian.org /debian-lts-announce/2025/07/msg00021.html
- cert-portal.siemens.com /productcert/html/ssa-637483.html
- cert-portal.siemens.com /productcert/html/ssa-794697.html
- cert-portal.siemens.com /productcert/html/ssa-398330.html
- cert-portal.siemens.com /productcert/html/ssa-202008.html
Sources
- CVE List CVE-2020-12762
- NVD CVE-2020-12762
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.