HOMEVULNERABILITIESCVE-2020-35963
HIGH

CVE-2020-35963

CWE-787Published: January 3, 2021· Updated: Jun 17, 2026

7.8
CVSS v3.1

Official Description

flb_gzip_compress in flb_gzip.c in Fluent Bit before 1.6.4 has an out-of-bounds write because it does not use the correct calculation of the maximum gzip data-size expansion.

NVD Source

Technical Analysis

CVE-2020-35963 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 7.8.

From a weakness classification perspective (CWE-787): Out-of-bounds write vulnerabilities can lead to data corruption, crashes, or arbitrary code execution.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorLocal
Attack ComplexityLow
Privileges Req.None
User InteractionRequired
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected Vendors & Products

Linux1 product(s)
linux kernel
treasuredata1 product(s)
fluent bit
Source: NVD CPE · 2 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/fluent/fluent-bit/commit/cadff53c093210404aed01c4cf586adb8caa07af
PATCHhttps://github.com/fluent/fluent-bit/commit/cadff53c093210404aed01c4cf586adb8caa07af
ADVISORYhttps://bugs.chromium.org/p/oss-fuzz/issues/detail?id=27261
ADVISORYhttps://fluentbit.io/announcements/v1.6.4/
ADVISORYhttps://bugs.chromium.org/p/oss-fuzz/issues/detail?id=27261
ADVISORYhttps://fluentbit.io/announcements/v1.6.4/

All References (6)

→
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=27261Exploit · Issue Tracking · Third Party Advisory
→
https://fluentbit.io/announcements/v1.6.4/Release Notes · Vendor Advisory
→
https://github.com/fluent/fluent-bit/commit/cadff53c093210404aed01c4cf586adb8caa07afPatch · Third Party Advisory
→
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=27261Exploit · Issue Tracking · Third Party Advisory
→
https://fluentbit.io/announcements/v1.6.4/Release Notes · Vendor Advisory
→
https://github.com/fluent/fluent-bit/commit/cadff53c093210404aed01c4cf586adb8caa07afPatch · Third Party Advisory

Quick Facts

CVE IDCVE-2020-35963
CVSS Score7.8 / 10
SeverityHIGH
WeaknessCWE-787
CISA KEVNo
Affected2 vendor(s)
PublishedJan 3, 2021

Related CVEs (CWE-787)

CVE-2018-17160
10.0
CVE-2015-0235
10.0
CVE-2018-6692
10.0
CVE-2018-2913
10.0
CVE-2019-5049
10.0
CVE-2004-1287
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2020-35963 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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