CVE-2021-40633
A memory leak (out-of-memory) in gif2rgb in util/gif2rgb.c in giflib 5.1.4 allows remote...
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.
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
8.8
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.
- Record
CVE-2021-40633- 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
- 5.1 Medium
AV:N/AC:H/Au:N/C:P/I:P/A:P - Weakness
- CWE-401
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2021-40633- Updated
- 2026-11-02
EUVDEUVD-2021-27807 No score
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.
- Record
EUVD-2021-27807- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-77hm-q3fv-fq9x
8.8
A memory leak (out-of-memory) in gif2rgb in util/gif2rgb.c in giflib 5.1.4 allows remote...
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.
- Record
GHSA-77hm-q3fv-fq9x- 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-401
- Updated
- 2026-11-02
OSVALPINE-CVE-2021-40633
8.8
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.
- Record
ALPINE-CVE-2021-40633- 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
OSVAZL-41515
8.8
CVE-2021-40633 affecting package giflib for versions less than 5.2.1-10
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.
- Record
AZL-41515- 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
Show 17 moreShow less
OSVBELL-CVE-2021-40633
8.8
- Record
BELL-CVE-2021-40633- 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
OSV
8.8
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.
- Record
CVE-2021-40633- 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-2021-40633
8.8
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.
- Record
DEBIAN-CVE-2021-40633- 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
OSVJLSEC-2026-816
8.8
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.
- Record
JLSEC-2026-816- 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
- 5.1 Medium
AV:N/AC:H/Au:N/C:P/I:P/A:P - Updated
- 2026-11-02
OSVOESA-2024-1595
8.8
giflib security update
giflib is a library of gif images and provides utilities for processing images.
Security Fix(es):
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.(CVE-2021-40633)
- Record
OESA-2024-1595- 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
OSVOESA-2024-1599
8.8
giflib security update
giflib is a library of gif images and provides utilities for processing images.
Security Fix(es):
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.(CVE-2021-40633)
- Record
OESA-2024-1599- 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
OSVOESA-2024-1602
8.8
giflib security update
giflib is a library of gif images and provides utilities for processing images.
Security Fix(es):
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.(CVE-2021-40633)
- Record
OESA-2024-1602- 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
OSVOESA-2024-1664
8.8
giflib security update
giflib is a library of gif images and provides utilities for processing images.
Security Fix(es):
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.(CVE-2021-40633)
- Record
OESA-2024-1664- 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
OSVOESA-2024-1665
8.8
giflib security update
giflib is a library of gif images and provides utilities for processing images.
Security Fix(es):
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.(CVE-2021-40633)
- Record
OESA-2024-1665- 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
OSVOESA-2024-1666
8.8
giflib security update
giflib is a library of gif images and provides utilities for processing images.
Security Fix(es):
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.(CVE-2021-40633)
- Record
OESA-2024-1666- 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-2021-40633
8.8
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.
- Record
UBUNTU-CVE-2021-40633- 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
OSVCLSA-2026-1787646995 No score
Fix CVE(s): CVE-2020-23922, CVE-2021-40633, CVE-2026-23868
- SECURITY UPDATE: heap buffer over-read in gif2rgb
- debian/patches/CVE-2020-23922.patch: bound each pixel index against the active color table before indexing ColorMap->Colors in DumpScreen2RGB in util/gif2rgb.c.
- CVE-2020-23922
- SECURITY UPDATE: memory leak leading to denial of service
- debian/patches/CVE-2021-40633.patch: free every ScreenBuffer row, not just the row-pointer array, at the end of GIF2RGB in util/gif2rgb.c.
- CVE-2021-40633
- SECURITY UPDATE: double free in GifMakeSavedImage
- debian/patches/CVE-2026-23868.patch: null out the heap pointers aliased by the shallow copy of CopyFrom, test the source record when deciding what to deep-copy, and restore ExtensionBlockCount after the extension blocks are copied, in lib/gifalloc.c.
- CVE-2026-23868
- Record
CLSA-2026-1787646995- Updated
- 2026-11-02
OSVopenSUSE-SU-2024:13723-1 No score
giflib-devel-32bit-5.2.2-1.1 on GA media
These are all security issues fixed in the giflib-devel-32bit-5.2.2-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2024:13723-1- Updated
- 2026-11-02
OSVROOT-OS-DEBIAN-12-CVE-2021-40633 No score
CVE-2021-40633 in giflib - Patched by Root
Root has patched CVE-2021-40633 in the giflib package for Root:Debian:12. Multiple fixed versions available.
- Record
ROOT-OS-DEBIAN-12-CVE-2021-40633- Updated
- 2026-11-02
OSVSUSE-SU-2024:0786-1 No score
Security update for giflib
This update for giflib fixes the following issues:
Update to version 5.2.2
- Fixes for CVE-2023-48161 (bsc#1217390), CVE-2022-28506 (bsc#1198880)
- #138 Documentation for obsolete utilities still installed
- #139: Typo in 'LZW image data' page ('110_2 = 4_10')
- #140: Typo in 'LZW image data' page ('LWZ')
- #141: Typo in 'Bits and bytes' page ('filed')
- Note as already fixed SF issue #143: cannot compile under mingw
- #144: giflib-5.2.1 cannot be build on windows and other platforms using c89
- #145: Remove manual pages installation for binaries that are not installed too
- #146: [PATCH] Limit installed man pages to binaries, move giflib to section 7
- #147 [PATCH] Fixes to doc/whatsinagif/ content
- #148: heap Out of Bound Read in gif2rgb.c:298 DumpScreen2RGB
- Declared no-info on SF issue #150: There is a denial of service vulnerability in GIFLIB 5.2.1
- Declared Won't-fix on SF issue 149: Out of source builds no longer possible
- #151: A heap-buffer-overflow in gif2rgb.c:294:45
- #152: Fix some typos on the html documentation and man pages
- #153: Fix segmentation faults due to non correct checking for args
- #154: Recover the giffilter manual page
- #155: Add gifsponge docs
- #157: An OutofMemory-Exception or Memory Leak in gif2rgb
- #158: There is a null pointer problem in gif2rgb
- #159 A heap-buffer-overflow in GIFLIB5.2.1 DumpScreen2RGB() in gif2rgb.c:298:45
- #163: detected memory leaks in openbsd_reallocarray giflib/openbsd-reallocarray.c
- #164: detected memory leaks in GifMakeMapObject giflib/gifalloc.c
- #166: a read zero page leads segment fault in getarg.c and memory leaks in gif2rgb.c and gifmalloc.c
- #167: Heap-Buffer Overflow during Image Saving in DumpScreen2RGB Function at Line 321 of gif2rgb.c
- Record
SUSE-SU-2024:0786-1- Updated
- 2026-11-02
OSVSUSE-SU-2024:1622-1 No score
Security update for giflib
This update for giflib fixes the following issues:
- CVE-2018-11490: Fixed a heap-based buffer overflow in DGifDecompressLine() (bsc#1094832)
- CVE-2021-40633: Fixed a denial of service from excessive memory (bsc#1200551)
- Record
SUSE-SU-2024:1622-1- Updated
- 2026-11-02
OSVUSN-6824-1 No score
giflib vulnerabilities
It was discovered that GIFLIB incorrectly handled certain GIF files. An attacker could possibly use this issue to cause a denial of service. (CVE-2021-40633, CVE-2022-28506, CVE-2023-39742)
- Record
USN-6824-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
giflibAlpine:v3.17 |
before 5.2.2-r0 | 5.2.2-r0 |
giflibAlpine:v3.18 |
before 5.2.2-r0 | 5.2.2-r0 |
giflibAlpine:v3.19 |
before 5.2.2-r0 | 5.2.2-r0 |
giflibAlpine:v3.20 |
before 5.2.2-r0 | 5.2.2-r0 |
giflibAlpine:v3.21 |
before 5.2.2-r0 | 5.2.2-r0 |
giflibAlpine:v3.22 |
before 5.2.2-r0 | 5.2.2-r0 |
giflibAlpine:v3.23 |
before 5.2.2-r0 | 5.2.2-r0 |
giflibAlpine:v3.24 |
before 5.2.2-r0 | 5.2.2-r0 |
giflibAzure Linux:3 |
before 5.2.1-10 | 5.2.1-10 |
giflibAlpaquita:23 |
5.2.1-r2 up to 5.2.2-r0 | 5.2.2-r0 |
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| Package | Affected | Fixed |
|---|---|---|
giflibAlpaquita:stream |
5.2.1-r5 up to 5.2.2-r0 | 5.2.2-r0 |
giflib-toolsTuxCare:Ubuntu:18.04 |
before 5.1.4-2ubuntu0.1+tuxcare.els1 | 5.1.4-2ubuntu0.1+tuxcare.els1 |
libgif-devTuxCare:Ubuntu:18.04 |
before 5.1.4-2ubuntu0.1+tuxcare.els1 | 5.1.4-2ubuntu0.1+tuxcare.els1 |
libgif7TuxCare:Ubuntu:18.04 |
before 5.1.4-2ubuntu0.1+tuxcare.els1 | 5.1.4-2ubuntu0.1+tuxcare.els1 |
giflibDebian:12 |
All versions, plus listed versions 5.2.1-2.55.2.1-2.5+deb12u15.2.2-16.1.3-1 |
None known |
giflibDebian:13 |
before 5.2.2-1 | 5.2.2-1 |
giflibDebian:14 |
before 5.2.2-1 | 5.2.2-1 |
Giflib_jllJulia |
before 5.2.1+0 | 5.2.1+0 |
giflibopenEuler:20.03-LTS-SP1 |
before 5.2.1-5.oe1 | 5.2.1-5.oe1 |
giflibopenEuler:20.03-LTS-SP4 |
before 5.2.1-5.oe2003sp4 | 5.2.1-5.oe2003sp4 |
giflibopenEuler:22.03-LTS |
before 5.2.1-6.oe2203 | 5.2.1-6.oe2203 |
giflibopenEuler:22.03-LTS-SP2 |
before 5.2.1-8.oe2203sp2 | 5.2.1-8.oe2203sp2 |
giflibopenEuler:22.03-LTS-SP3 |
before 5.2.1-8.oe2203sp3 | 5.2.1-8.oe2203sp3 |
giflibopenEuler:22.03-LTS-SP1 |
before 5.2.1-8.oe2203sp1 | 5.2.1-8.oe2203sp1 |
giflibRoot:Debian:12 |
before 5.2.1-2.5+deb12u1.aikido.8 | 5.2.1-2.5+deb12u1.aikido.8 |
rootio-giflibRoot:Debian:12 |
before 5.2.1-2.5+deb12u1.aikido.8 | 5.2.1-2.5+deb12u1.aikido.8 |
giflibSUSE:Linux Enterprise Module for Basesystem 15 SP5 |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Linux Enterprise Server 15 SP2-LTSS |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Linux Enterprise Server 15 SP3-LTSS |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Linux Enterprise Server 15 SP4-LTSS |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Linux Enterprise Server for SAP Applications 15 SP2 |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Linux Enterprise Server for SAP Applications 15 SP3 |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Linux Enterprise Server for SAP Applications 15 SP4 |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Manager Proxy 4.3 |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Manager Server 4.3 |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Enterprise Storage 7.1 |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibopenSUSE:Leap 15.5 |
before 5.2.2-150000.4.13.1 | 5.2.2-150000.4.13.1 |
giflibSUSE:Linux Enterprise Software Development Kit 12 SP5 |
before 5.0.5-13.3.1 | 5.0.5-13.3.1 |
giflibSUSE:Linux Enterprise Server 12 SP5 |
before 5.0.5-13.3.1 | 5.0.5-13.3.1 |
giflibSUSE:Linux Enterprise Server for SAP Applications 12 SP5 |
before 5.0.5-13.3.1 | 5.0.5-13.3.1 |
giflibUbuntu:Pro:16.04:LTS |
before 5.1.4-0.3~16.04.1+esm1, plus listed versions 4.1.6-115.1.1-0ubuntu15.1.1-0.15.1.1-0.25.1.2-0.15.1.2-0.25.1.4-0.3~16.045.1.4-0.3~16.04.1 |
5.1.4-0.3~16.04.1+esm1 |
giflibUbuntu:Pro:18.04:LTS |
before 5.1.4-2ubuntu0.1+esm1, plus listed versions 5.1.4-15.1.4-25.1.4-2ubuntu0.1 |
5.1.4-2ubuntu0.1+esm1 |
giflibUbuntu:20.04:LTS |
before 5.1.9-1ubuntu0.1, plus listed versions 5.1.4-3ubuntu15.1.9-1 |
5.1.9-1ubuntu0.1 |
giflibUbuntu:22.04:LTS |
before 5.1.9-2ubuntu0.1, plus listed versions 5.1.9-2build15.1.9-2build2 |
5.1.9-2ubuntu0.1 |
giflibopenSUSE:Tumbleweed |
before 5.2.2-1.1 | 5.2.2-1.1 |
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-2021-40633 is a high vulnerability (CVSS 8.8) in Giflib Project Giflib, published June 14, 2022. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.72%, the 77th percentile. Fixed in giflib 5.2.2-r0.
References
sourceforge.net/p/giflib/bugs/157
nvd.nist.gov/vuln/detail/CVE-2021-40633
github.com/advisories/GHSA-77hm-q3fv-fq9x
security.alpinelinux.org/vuln/CVE-2021-40633
docs.bell-sw.com/security/cves/CVE-2021-40633
errata.tuxcare.com/els_os/ubuntu18.04els/CLSA-2026-1787646995.html
Show 25 moreShow less
nvd.nist.gov/vuln/detail/CVE-2020-23922
nvd.nist.gov/vuln/detail/CVE-2026-23868
security-tracker.debian.org/tracker/CVE-2021-40633
openeuler.org/en/security/safety-bulletin/detail.html?id=openEuler-SA-2024-1595
openeuler.org/en/security/safety-bulletin/detail.html?id=openEuler-SA-2024-1599
openeuler.org/en/security/safety-bulletin/detail.html?id=openEuler-SA-2024-1602
openeuler.org/en/security/safety-bulletin/detail.html?id=openEuler-SA-2024-1664
openeuler.org/en/security/safety-bulletin/detail.html?id=openEuler-SA-2024-1665
openeuler.org/en/security/safety-bulletin/detail.html?id=openEuler-SA-2024-1666
suse.com/support/update/announcement/2024/suse-su-20240786-1
bugzilla.suse.com/1198880
bugzilla.suse.com/1200551
bugzilla.suse.com/1217390
suse.com/security/cve/CVE-2021-40633
suse.com/security/cve/CVE-2022-28506
suse.com/security/cve/CVE-2023-48161
suse.com/support/update/announcement/2024/suse-su-20241622-1
bugzilla.suse.com/1094832
suse.com/security/cve/CVE-2018-11490
ubuntu.com/security/CVE-2021-40633
cve.org/CVERecord?id=CVE-2021-40633
ubuntu.com/security/notices/USN-6824-1
ubuntu.com/security/CVE-2022-28506
ubuntu.com/security/CVE-2023-39742
suse.com/security/cve/CVE-2019-15133