CVE-2021-40633

Exp

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.

Published: 2022-06-14 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-40633 is rated High Exploit Risk (75.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.52%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-40633

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-40633

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.81% 1.52% +0.71%
2 2025-12-18 1.10% 0.81% -0.29%
3 2025-11-21 — 1.10% —

Full EPSS history (18 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-40633

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.8 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 [email protected]
5.1 2.0 MEDIUM
AV:N/AC:H/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:H)
Exploitation requires uncommon or highly specific conditions.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 4.9 6.4 [email protected]

Weakness enumeration for CVE-2021-40633

OS Trackers for CVE-2021-40633

vendor priority summary link
alpine — CVE-2021-40633: 1 source package rows (giflib); 7 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 7, open 0. https://security.alpinelinux.org/vuln/CVE-2021-40633
debian unimportant CVE-2021-40633 unimportant priority: Debian including 1 source packages (giflib), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2. https://security-tracker.debian.org/tracker/CVE-2021-40633
redhat high — https://access.redhat.com/security/cve/CVE-2021-40633
suse low CVE-2021-40633 severity low: SUSE including 265 source package names (10.1.33-openjdk11-59.4:libgif7-5.2.2-150000.4.13.1, 10.1.33-openjdk17-59.4:libgif7-5.2.2-150000.4.13.1, …), 367 product×package rows across 65 product lines (Container bci/openjdk, Container bci/openjdk-devel, … (65 product lines)): Known Affected 231, Fixed 95, Known Not Affected 41. https://www.suse.com/security/cve/CVE-2021-40633/
ubuntu low CVE-2021-40633 low priority: Ubuntu including 1 source packages (giflib), 10 status rows across 10 suites (bionic, focal, impish, jammy, kinetic, lunar, mantic, noble, upstream, xenial): released 5, ignored 3, needs-triage 1, not-affected 1. https://ubuntu.com/security/CVE-2021-40633

Affected software / configurations for CVE-2021-40633

Vendor Product Version Raw CPE
giflib_project giflib 5.1.4 cpe:2.3:a:giflib_project:giflib:5.1.4:*:*:*:*:*:*:*

References for CVE-2021-40633

URL Tags
https://sourceforge.net/p/giflib/bugs/157/ Exploit Issue Tracking Third Party Advisory
cvelogic Threat Intelligence