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CVE-2026-49839

Jqlang Jq buffer overflow

7.1 HIGHPublic exploitEPSS 0.17%
  1. Published25 Jun 2026

Description

jq is a command-line JSON processor. Prior to 1.8.2,` jq --rawfile` can turn a handled oversized-string error into invalid-state reuse and a real heap out-of-bounds write in assertion-disabled builds. When jv_load_file(raw=1) reads an attacker-controlled file, it repeatedly appends file chunks to the same jv string accumulator. Once jv_string_append_buf() returns jv_invalid_with_msg("String too long"), the raw-file loop does not stop. If the file contains at least one more byte, the next loop iteration appends a new chunk to an object that is already invalid. With assertions enabled this aborts in jvp_string_ptr(). With assertions disabled, the invalid object is interpreted as a string object and ASan reports heap-buffer-overflow. This vulnerability is fixed in 1.8.2.

CVSS 3.1 breakdown

Attack vectorLocal
Attack complexityLow
Privileges requiredNone
User interactionRequired
ScopeUnchanged
ConfidentialityNone
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H

Affected products

Jqlang Jq< 1.8.2

Remediation

Fixed in
Jqlang Jq≥ 1.8.2

References

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Frequently asked

Is CVE-2026-49839 being actively exploited?

CVE-2026-49839 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.17%.

How severe is CVE-2026-49839?

CVE-2026-49839 has a CVSS 3.1 base score of 7.1, rated high. EPSS estimates a 0.17% probability of exploitation.

Which products are affected by CVE-2026-49839?

Affected products include Jqlang Jq.

How do I fix CVE-2026-49839?

Upgrade affected software to a fixed version, for example Jqlang Jq 1.8.2 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.