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CVE-2020-21548

Libsixel 1.8.3 contains a heap-based buffer overflow in the sixel_encode_highcolor function in...

8.8 HighFix available

Libsixel 1.8.3 contains a heap-based buffer overflow in the sixel_encode_highcolor function in tosixel.c.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

1.06%Up 0.6 points since Sep 18, 2021
90%50%10%1%

What each source reports

NVD Score used 8.8

Libsixel 1.8.3 contains a heap-based buffer overflow in the sixel_encode_highcolor function in tosixel.c.

Record
CVE-2020-21548
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS 2.0
6.8 MediumAV:N/AC:M/Au:N/C:P/I:P/A:P
Weakness
CWE-787
Updated
2026-11-02
CVE List No score

Libsixel 1.8.3 contains a heap-based buffer overflow in the sixel_encode_highcolor function in tosixel.c.

Record
CVE-2020-21548
Updated
2026-11-02
EUVDEUVD-2020-14316 No score

Libsixel 1.8.3 contains a heap-based buffer overflow in the sixel_encode_highcolor function in tosixel.c.

Record
EUVD-2020-14316
Updated
2026-11-03
GitHub AdvisoriesGHSA-rqxx-8p8c-6h26 8.8

Libsixel 1.8.3 contains a heap-based buffer overflow in the sixel_encode_highcolor function in...

Libsixel 1.8.3 contains a heap-based buffer overflow in the sixel_encode_highcolor function in tosixel.c.

Record
GHSA-rqxx-8p8c-6h26
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-787
Updated
2026-11-02
OSV 8.8

Libsixel 1.8.3 contains a heap-based buffer overflow in the sixel_encode_highcolor function in tosixel.c.

Record
CVE-2020-21548
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2020-21548 8.8

Libsixel 1.8.3 contains a heap-based buffer overflow in the sixel_encode_highcolor function in tosixel.c.

Record
DEBIAN-CVE-2020-21548
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2020-21548 8.8

Libsixel 1.8.3 contains a heap-based buffer overflow in the sixel_encode_highcolor function in tosixel.c.

Record
UBUNTU-CVE-2020-21548
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
libsixel
Debian:12
 before 1.8.6-1
1.8.6-1
libsixel
Debian:13
 before 1.8.6-1
1.8.6-1
libsixel
Debian:14
 before 1.8.6-1
1.8.6-1
libsixel
Ubuntu:16.04:LTS
 All versions, plus listed versions
1.4.2-11.5.2-2
 None known
libsixel
Ubuntu:18.04:LTS
 All versions, plus listed versions
1.5.2-21.7.3-1
 None known
libsixel
Ubuntu:20.04:LTS
 All versions, plus listed versions
1.8.2-11.8.2-2.1
 None known

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

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

In short

CVE-2020-21548 is a high vulnerability (CVSS 8.8) in Saitoha Libsixel, published September 17, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.06%, the 64th percentile. Fixed in libsixel 1.8.6-1.

References

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