CVE-2026-116591

compress zstd: Panic on two-block frames

Published Oct 26, 2026 CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed
Description
compress provides various compression algorithms. Prior to 1.20.2, the zstd DecodeAll and streaming decoder paths can panic when a crafted two-block frame reaches huff0.ReadTable with an FSE normalized count of 32768 that readNCount stores in int16 as -32768. The wrapped count allows buildDtable to retain stale fse.Scratch decode-table state from the prior block, and nextFast then derives an out-of-range state and indexes beyond the table instead of returning a decode error. Both blocks are required to preserve and then reuse the stale state, allowing untrusted zstd input to crash an application. This issue is fixed in version 1.20.2.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-fpmh-frq8-7rj8 compress zstd: Panic on two-block frames
History
Type Values Removed Values Added
Weaknesses CWE-125
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Klauspost
Klauspost compress
Vendors & Products Klauspost
Klauspost compress
Type Values Removed Values Added
Description compress provides various compression algorithms. Prior to 1.20.2, the zstd DecodeAll and streaming decoder paths can panic when a crafted two-block frame reaches huff0.ReadTable with an FSE normalized count of 32768 that readNCount stores in int16 as -32768. The wrapped count allows buildDtable to retain stale fse.Scratch decode-table state from the prior block, and nextFast then derives an out-of-range state and indexes beyond the table instead of returning a decode error. Both blocks are required to preserve and then reuse the stale state, allowing untrusted zstd input to crash an application. This issue is fixed in version 1.20.2.
Title compress zstd: Panic on two-block frames
Weaknesses CWE-190
References
Metrics cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Oct 27, 2026, 2:16 PM
Reserved
Oct 26, 2026, 3:03 PM
Status
Awaiting Analysis
Published
Oct 26, 2026, 10:16 PM
Modified
Oct 27, 2026, 4:03 PM
Severity
Important
Public date
Oct 26, 2026, 9:54 PM