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CVE-2026-16554

Integer Overflow Leading to Heap Buffer Overflow in cJSON

5.1 MediumFix available

cJSON library is vulnerable to an integer overflow in the print_string_ptr() function in cJSON.c on 32-bit platforms. The escape_characters counter, a 32-bit size_t, can wrap around when processing strings containing approximately 858,993,460 or more control characters, causing the output buffer to be allocated based on an underestimated length. When cJSON_PrintBuffered() is used with a pre-allocated buffer, the subsequent write loop overflows the heap allocation. An attacker supplying a crafted JSON string to an application using cJSON on a 32-bit platform can cause a heap buffer overflow, potentially leading to remote code execution, information disclosure, or denial of service.

Because project creator contact attempts were unsuccessful, the vulnerability has only been confirmed in version 1.7.19 but may also affect other versions.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
Low

Exploit likelihood

0.37%Up 0.1 points since Jul 28, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.1

Integer Overflow Leading to Heap Buffer Overflow in cJSON

cJSON library is vulnerable to an integer overflow in the print_string_ptr() function in cJSON.c on 32-bit platforms. The escape_characters counter, a 32-bit size_t, can wrap around when processing strings containing approximately 858,993,460 or more control characters, causing the output buffer to be allocated based on an underestimated length. When cJSON_PrintBuffered() is used with a pre-allocated buffer, the subsequent write loop overflows the heap allocation. An attacker supplying a crafted JSON string to an application using cJSON on a 32-bit platform can cause a heap buffer overflow, potentially leading to remote code execution, information disclosure, or denial of service.

Because project creator contact attempts were unsuccessful, the vulnerability has only been confirmed in version 1.7.19 but may also affect other versions.

Record
CVE-2026-16554
CVSS 4.0
5.1 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:L/SI:L/SA:L
Weakness
CWE-190
Updated
2026-11-02
EUVDEUVD-2026-49129 5.1

cJSON library is vulnerable to an integer overflow in the print_string_ptr() function in cJSON.c on 32-bit platforms. The escape_characters counter, a 32-bit size_t, can wrap around when processing strings containing approximately 858,993,460 or more control characters, causing the output buffer to be allocated based on an underestimated length. When cJSON_PrintBuffered() is used with a pre-allocated buffer, the subsequent write loop overflows the heap allocation. An attacker supplying a crafted JSON string to an application using cJSON on a 32-bit platform can cause a heap buffer overflow, potentially leading to remote code execution, information disclosure, or denial of service.

Because project creator contact attempts were unsuccessful, the vulnerability has only been confirmed in version 1.7.19 but may also affect other versions.

Record
EUVD-2026-49129
CVSS 4.0
5.1 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:L/SI:L/SA:L
Updated
2026-11-02
GitHub AdvisoriesGHSA-qv6q-8g2j-w47g 5.1

cJSON library is vulnerable to an integer overflow in the print_string_ptr() function in cJSON.c...

cJSON library is vulnerable to an integer overflow in the print_string_ptr() function in cJSON.c on 32-bit platforms. The escape_characters counter, a 32-bit size_t, can wrap around when processing strings containing approximately 858,993,460 or more control characters, causing the output buffer to be allocated based on an underestimated length. When cJSON_PrintBuffered() is used with a pre-allocated buffer, the subsequent write loop overflows the heap allocation. An attacker supplying a crafted JSON string to an application using cJSON on a 32-bit platform can cause a heap buffer overflow, potentially leading to remote code execution, information disclosure, or denial of service.

Because project creator contact attempts were unsuccessful, the vulnerability has only been confirmed in version 1.7.19 but may also affect other versions.

Record
GHSA-qv6q-8g2j-w47g
CVSS 4.0
5.1 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-190
Updated
2026-11-02
NVD 5.1

cJSON library is vulnerable to an integer overflow in the print_string_ptr() function in cJSON.c on 32-bit platforms. The escape_characters counter, a 32-bit size_t, can wrap around when processing strings containing approximately 858,993,460 or more control characters, causing the output buffer to be allocated based on an underestimated length. When cJSON_PrintBuffered() is used with a pre-allocated buffer, the subsequent write loop overflows the heap allocation. An attacker supplying a crafted JSON string to an application using cJSON on a 32-bit platform can cause a heap buffer overflow, potentially leading to remote code execution, information disclosure, or denial of service.

Because project creator contact attempts were unsuccessful, the vulnerability has only been confirmed in version 1.7.19 but may also affect other versions.

Record
CVE-2026-16554
CVSS 4.0
5.1 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-190
Updated
2026-11-02
OSV 5.1

Integer Overflow Leading to Heap Buffer Overflow in cJSON

cJSON library is vulnerable to an integer overflow in the print_string_ptr() function in cJSON.c on 32-bit platforms. The escape_characters counter, a 32-bit size_t, can wrap around when processing strings containing approximately 858,993,460 or more control characters, causing the output buffer to be allocated based on an underestimated length. When cJSON_PrintBuffered() is used with a pre-allocated buffer, the subsequent write loop overflows the heap allocation. An attacker supplying a crafted JSON string to an application using cJSON on a 32-bit platform can cause a heap buffer overflow, potentially leading to remote code execution, information disclosure, or denial of service.

Because project creator contact attempts were unsuccessful, the vulnerability has only been confirmed in version 1.7.19 but may also affect other versions.

Record
CVE-2026-16554
CVSS 4.0
5.1 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:L/SI:L/SA:L
Weakness
CWE-190
Updated
2026-11-02
OSVDEBIAN-CVE-2026-16554 7.8

cJSON library is vulnerable to an integer overflow in the print_string_ptr() function in cJSON.c on 32-bit platforms. The escape_characters counter, a 32-bit size_t, can wrap around when processing strings containing approximately 858,993,460 or more control characters, causing the output buffer to be allocated based on an underestimated length. When cJSON_PrintBuffered() is used with a pre-allocated buffer, the subsequent write loop overflows the heap allocation. An attacker supplying a crafted JSON string to an application using cJSON on a 32-bit platform can cause a heap buffer overflow, potentially leading to remote code execution, information disclosure, or denial of service. Because project creator contact attempts were unsuccessful, the vulnerability has only been confirmed in version 1.7.19 but may also affect other versions.

Record
DEBIAN-CVE-2026-16554
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
Show 5 moreShow less
OSVUBUNTU-CVE-2026-16554 5.1

cJSON library is vulnerable to an integer overflow in the print_string_ptr() function in cJSON.c on 32-bit platforms. The escape_characters counter, a 32-bit size_t, can wrap around when processing strings containing approximately 858,993,460 or more control characters, causing the output buffer to be allocated based on an underestimated length. When cJSON_PrintBuffered() is used with a pre-allocated buffer, the subsequent write loop overflows the heap allocation. An attacker supplying a crafted JSON string to an application using cJSON on a 32-bit platform can cause a heap buffer overflow, potentially leading to remote code execution, information disclosure, or denial of service. Because project creator contact attempts were unsuccessful, the vulnerability has only been confirmed in version 1.7.19 but may also affect other versions.

Record
UBUNTU-CVE-2026-16554
CVSS 4.0
5.1 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:L/SI:L/SA:L
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVAZL-94184 No score

CVE-2026-16554 affecting package apparmor 3.1.7-1

cJSON library is vulnerable to an integer overflow in the print_string_ptr() function in cJSON.c on 32-bit platforms. The escape_characters counter, a 32-bit size_t, can wrap around when processing strings containing approximately 858,993,460 or more control characters, causing the output buffer to be allocated based on an underestimated length. When cJSON_PrintBuffered() is used with a pre-allocated buffer, the subsequent write loop overflows the heap allocation. An attacker supplying a crafted JSON string to an application using cJSON on a 32-bit platform can cause a heap buffer overflow, potentially leading to remote code execution, information disclosure, or denial of service.

Because project creator contact attempts were unsuccessful, the vulnerability has only been confirmed in version 1.7.19 but may also affect other versions.

Record
AZL-94184
Updated
2026-11-05
OSVAZL-94244 No score

CVE-2026-16554 affecting package libglvnd 1.7.0-3

cJSON library is vulnerable to an integer overflow in the print_string_ptr() function in cJSON.c on 32-bit platforms. The escape_characters counter, a 32-bit size_t, can wrap around when processing strings containing approximately 858,993,460 or more control characters, causing the output buffer to be allocated based on an underestimated length. When cJSON_PrintBuffered() is used with a pre-allocated buffer, the subsequent write loop overflows the heap allocation. An attacker supplying a crafted JSON string to an application using cJSON on a 32-bit platform can cause a heap buffer overflow, potentially leading to remote code execution, information disclosure, or denial of service.

Because project creator contact attempts were unsuccessful, the vulnerability has only been confirmed in version 1.7.19 but may also affect other versions.

Record
AZL-94244
Updated
2026-11-05
OSVROOT-OS-ALPINE-321-CVE-2026-16554 No score

CVE-2026-16554 in cjson - Patched by Root

Root has patched CVE-2026-16554 in the cjson package for Root:Alpine:3.21. Multiple fixed versions available.

Record
ROOT-OS-ALPINE-321-CVE-2026-16554
Updated
2026-11-02
OSVROOT-OS-ALPINE-323-CVE-2026-16554 No score

CVE-2026-16554 in cjson - Patched by Root

Root has patched CVE-2026-16554 in the cjson package for Root:Alpine:3.23. Multiple fixed versions available.

Record
ROOT-OS-ALPINE-323-CVE-2026-16554
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
apparmor
Azure Linux:3
through 3.1.7-1 None known
libglvnd
Azure Linux:3
through 1.7.0-3 None known
cjson
Debian:12
All versions, plus listed versions
1.7.15-11.7.15-1+deb12u11.7.15-1+deb12u21.7.15-1+deb12u31.7.15-1+deb12u4
Show 11 moreShow less
1.7.16-11.7.16-21.7.17-11.7.17-21.7.18-11.7.18-21.7.18-31.7.18-3.11.7.18-41.7.19-11.7.19-2
None known
cjson
Debian:13
All versions, plus listed versions
1.7.18-3.11.7.18-3.1+deb13u11.7.18-41.7.19-11.7.19-2
None known
cjson
Debian:14
All versions, plus listed versions
1.7.18-3.11.7.18-41.7.19-11.7.19-2
None known
cjson
Root:Alpine:3.21
before 1.7.19-r00072
1.7.19-r000721.7.19-r00071
rootio-cjson
Root:Alpine:3.21
before 1.7.19-r00072
1.7.19-r000721.7.19-r00071
cjson
Root:Alpine:3.23
before 1.7.19-r10071
1.7.19-r100711.7.19-r100741.7.19-r100721.7.19-r10073
rootio-cjson
Root:Alpine:3.23
before 1.7.19-r10071
1.7.19-r100711.7.19-r100741.7.19-r100721.7.19-r10073
cjson
Ubuntu:Pro:20.04:LTS
All versions, plus listed versions
1.7.10-1.11.7.10-1.1ubuntu0.1~esm1
None known
Show 4 moreShow less
Affected packages
PackageAffectedFixed
cjson
Ubuntu:Pro:22.04:LTS
All versions, plus listed versions
1.7.14-11.7.15-11.7.15-1ubuntu0.1~esm21.7.15-1ubuntu0.11.7.15-1ubuntu0.1+esm1
None known
cjson
Ubuntu:Pro:24.04:LTS
All versions, plus listed versions
1.7.16-11.7.16-21.7.17-11.7.17-1ubuntu0.1~esm21.7.17-1ubuntu0.1~esm3
None known
cjson
Ubuntu:26.10
All versions, plus listed versions
1.7.19-2
None known
cjson
Ubuntu:26.04:LTS
All versions, plus listed versions
1.7.18-3.11.7.18-41.7.19-11.7.19-2
None known

History

History
RecordedChangedSources
factsOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-16554 is a medium vulnerability (CVSS 5.1) in Cjson Project Cjson, published July 27, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.37%, the 30th percentile. Fixed in cjson 1.7.19-r00072.

References

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