CVE-2021-40656
CVE-2021-40656 is a high-severity vulnerability in Libsixel with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.
Key facts
- Severity: High (CVSS 3.x base score 8.8)
- CVSS v2: 6.8
- EPSS exploit prediction: 1% (59th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-787
- Affected product: Libsixel
- Published:
- Last modified:
Description
libsixel before 1.10 is vulnerable to Buffer Overflow in libsixel/src/quant.c:867.
Frequently asked questions
- What is CVE-2021-40656?
- libsixel before 1.10 is vulnerable to Buffer Overflow in libsixel/src/quant.c:867.
- How severe is CVE-2021-40656?
- CVE-2021-40656 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2021-40656 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-40656?
- CVE-2021-40656 affects Libsixel. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2021-40656?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2021-40656 published?
- CVE-2021-40656 was published on 2022-04-08 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:libsixel:libsixel:*:*:*:*:*:*:*:*
More vulnerabilities in Libsixel
- CVE-2021-41715 — High (CVSS 8.8): libsixel 1.10.0 is vulnerable to Use after free in libsixel/src/dither.c:379.
- CVE-2021-45340 — Medium (CVSS 6.5): In Libsixel prior to and including v1.10.3, a NULL pointer dereference in the stb_image.h component of libsixel allows…
- CVE-2022-27938 — Medium (CVSS 5.5): stb_image.h (aka the stb image loader) 2.19, as used in libsixel and other products, has a reachable assertion in…
Other CWE-787 (Out-of-bounds Write) vulnerabilities
- CVE-2026-42369 — Critical (CVSS 10.0): GV-VMS V20 is a Video Monitoring Software used to gather the feeds of many surveillance cameras and manage other…
- CVE-2026-4746 — Critical (CVSS 10.0): Out-of-bounds Write vulnerability in timeplus-io proton (base/poco/Foundation/src modules). This vulnerability is…
- CVE-2025-43300 — Critical (CVSS 10.0): An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 15.8.5 and iPadOS…
- CVE-2025-24201 — Critical (CVSS 10.0): An out-of-bounds write issue was addressed with improved checks to prevent unauthorized actions. This issue is fixed in…
- CVE-2024-42479 — Critical (CVSS 10.0): llama.cpp provides LLM inference in C/C++. The unsafe `data` pointer member in the `rpc_tensor` structure can cause…
- CVE-2024-39791 — Critical (CVSS 10.0): Stack-based buffer overflow vulnerabilities affecting Vonets industrial wifi bridge relays and wifi bridge…