CVE-2026-39979
Description
A flaw was found in jq, a command line JSON processor, specifically in the libjq API. Parsing a malformed JSON input from a non-NUL-terminated buffer using the jv_parse_sized function can cause an out-of-bounds read, resulting in an application crash and a possible memory disclosure within the error message generated by the parser.
Statement
To exploit this flaw, an attacker needs to supply malformed JSON from a non-NUL-terminated buffer to an application using the jv_parse_sized function. This allows the attacker to trigger the out-of-bounds read, causing an application crash and potentially disclosing memory with no other security impact. As this issue affects the libjq library, it is more likely to be exposed to untrusted input. Due to these reasons, this vulnerability has been rated with an important severity.
Mitigation
To mitigate this issue, manually ensure that every buffer is NUL-terminated before passing it to the 'jv_parse_sized' function.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.2 | 6.5 | 8.2 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | Low | Low | Low |
| Integrity Impact | None | None | None |
| Availability Impact | High | Low | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
An attacker could get secret values such as cryptographic keys, PII, memory addresses, or other information that could be used in additional attacks.
Confidentiality
Technical Impact: Bypass Protection Mechanism
Out-of-bounds memory could contain memory addresses or other information that can be used to bypass ASLR and other protection mechanisms in order to improve the reliability of exploiting a separate weakness for code execution.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker could cause a segmentation fault or crash by causing memory to be read outside of the bounds of the buffer. This is especially likely when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string.
Other
Technical Impact: Varies by Context
The read operation could produce other undefined or unexpected results.
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