How severe is CVE-2021-40633?

CVE-2021-40633 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-2021-40633 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40633?

CVE-2021-40633 affects Giflib Project Giflib. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-40633?

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-2021-40633 published?

CVE-2021-40633 was published on 2022-06-14 and last updated on 2026-06-17.

CVE-2021-40633

CVE-2021-40633 is a high-severity vulnerability in Giflib Project Giflib 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-401.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 5.1
EPSS exploit prediction: 2% (74th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-401
Affected product: Giflib Project Giflib
Published: 2022-06-14
Last modified: 2026-06-17

Description

A memory leak (out-of-memory) in gif2rgb in util/gif2rgb.c in giflib 5.1.4 allows remote attackers trigger an out of memory exception or denial of service via a gif format file.

Frequently asked questions

What is CVE-2021-40633?: A memory leak (out-of-memory) in gif2rgb in util/gif2rgb.c in giflib 5.1.4 allows remote attackers trigger an out of memory exception or denial of service via a gif format file.
How severe is CVE-2021-40633?: CVE-2021-40633 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-2021-40633 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40633?: CVE-2021-40633 affects Giflib Project Giflib. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-40633?: 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-2021-40633 published?: CVE-2021-40633 was published on 2022-06-14 and last updated on 2026-06-17.

References

https://sourceforge.net/p/giflib/bugs/157/

Affected products (1)

cpe:2.3:a:giflib_project:giflib:5.1.4:*:*:*:*:*:*:*

More vulnerabilities in Giflib Project Giflib

CVE-2016-3177 — Critical (CVSS 9.8): Multiple use-after-free and double-free vulnerabilities in gifcolor.c in GIFLIB 5.1.2 have unspecified impact and…
CVE-2018-11490 — High (CVSS 8.8): The DGifDecompressLine function in dgif_lib.c in GIFLIB (possibly version 3.0.x), as later shipped in cgif.c in sam2p…
CVE-2018-11489 — High (CVSS 8.8): The DGifDecompressLine function in dgif_lib.c in GIFLIB (possibly version 3.0.x), as later shipped in cgif.c in sam2p…
CVE-2026-26740 — High (CVSS 8.2): Buffer Overflow vulnerability in giflib v.5.2.2 allows a remote attacker to cause a denial of service via the…
CVE-2023-48161 — High (CVSS 7.1): Buffer Overflow vulnerability in GifLib Project GifLib v.5.2.1 allows a local attacker to obtain sensitive information…
CVE-2020-23922 — High (CVSS 7.1): An issue was discovered in giflib through 5.1.4. DumpScreen2RGB in gif2rgb.c has a heap-based buffer over-read.

All CVEs affecting Giflib Project Giflib →

Other CWE-401 (Missing Release of Memory after Effective Lifetime) vulnerabilities

CVE-2026-46289 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: lib/scatterlist: fix length calculations in…
CVE-2025-39948 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: ice: fix Rx page leak on multi-buffer frames The…
CVE-2025-21954 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: netmem: prevent TX of unreadable skbs Currently…
CVE-2024-57947 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_set_pipapo: fix initial map…
CVE-2024-56779 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: nfsd: fix nfs4_openowner leak when concurrent…
CVE-2024-36911 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: hv_netvsc: Don't free decrypted memory In CoCo…

Browse all CWE-401 (Missing Release of Memory after Effective Lifetime) vulnerabilities →