CVE-2021-40656
libsixel before 1.10 is vulnerable to Buffer Overflow in libsixel/src/quant.c:867.
libsixel before 1.10 is vulnerable to Buffer Overflow in libsixel/src/quant.c:867.
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
What each source reports
NVD Score used
libsixel before 1.10 is vulnerable to Buffer Overflow in libsixel/src/quant.c:867.
- Record
CVE-2021-40656- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - CVSS 2.0
- 6.8 Medium
AV:N/AC:M/Au:N/C:P/I:P/A:P - Weakness
- CWE-787
- Updated
- 2026-11-02
CVE List No score
libsixel before 1.10 is vulnerable to Buffer Overflow in libsixel/src/quant.c:867.
- Record
CVE-2021-40656- Updated
- 2026-11-02
EUVDEUVD-2021-27830 No score
libsixel before 1.10 is vulnerable to Buffer Overflow in libsixel/src/quant.c:867.
- Record
EUVD-2021-27830- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-46hw-rjq2-89r4
libsixel before 1.10 is vulnerable to Buffer Overflow in libsixel/src/quant.c:867.
libsixel before 1.10 is vulnerable to Buffer Overflow in libsixel/src/quant.c:867.
- Record
GHSA-46hw-rjq2-89r4- CVSS 3.1
- 8.8 High
CVSS: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
libsixel before 1.10 is vulnerable to Buffer Overflow in libsixel/src/quant.c:867.
- Record
CVE-2021-40656- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVDEBIAN-CVE-2021-40656
libsixel before 1.10 is vulnerable to Buffer Overflow in libsixel/src/quant.c:867.
- Record
DEBIAN-CVE-2021-40656- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2021-40656
libsixel before 1.10 is vulnerable to Buffer Overflow in libsixel/src/quant.c:867.
- Record
UBUNTU-CVE-2021-40656- CVSS 3.1
- 8.8 High
CVSS: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
| Package | Affected | Fixed |
|---|---|---|
libsixelDebian:12 |
before 1.10.3-1 | 1.10.3-1 |
libsixelDebian:13 |
before 1.10.3-1 | 1.10.3-1 |
libsixelDebian:14 |
before 1.10.3-1 | 1.10.3-1 |
libsixelUbuntu:16.04:LTS |
All versions, plus listed versions 1.4.2-11.5.2-2 |
None known |
libsixelUbuntu:18.04:LTS |
All versions, plus listed versions 1.5.2-21.7.3-1 |
None known |
libsixelUbuntu:20.04:LTS |
All versions, plus listed versions 1.8.2-11.8.2-2.1 |
None known |
libsixelUbuntu:22.04:LTS |
All versions, plus listed versions 1.8.6-21.10.3-21.10.3-3 |
None known |
libsixelUbuntu:24.04:LTS |
All versions, plus listed versions 1.10.3-31.10.3-3build1 |
None known |
libsixelUbuntu:25.10 |
All versions, plus listed versions 1.10.5-1 |
None known |
libsixelUbuntu:26.10 |
All versions, plus listed versions 1.10.5-1build11:1.8.7-r2-1 |
None known |
libsixelUbuntu:26.04:LTS |
All versions, plus listed versions 1.10.5-11.10.5-1build1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-40656 is a high vulnerability (CVSS 8.8) in Libsixel, published April 8, 2022. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.02%, the 63rd percentile. Fixed in libsixel 1.10.3-1.