Security readout for executives and security teams
Plain-English summary
CVE-2021-40633 describes a memory leak in gif2rgb in giflib 5.1.4. A malicious GIF file can exhaust memory and cause denial of service when processed. The source bundle does not show code execution, data theft, active exploitation, or affected versions beyond giflib 5.1.4.
Executive priority
Treat this as an availability risk, not a confirmed breach risk. Prioritize internet-facing or business-critical image processing services first, especially where users can upload GIFs. Urgency is lower if gif2rgb is absent or only processes trusted files.
Technical view
The reported flaw is an out-of-memory condition in util/gif2rgb.c. Processing a GIF-format file through gif2rgb can leak memory until the process or host fails availability. The provided records do not include CVSS, CWE, fixed-version, or detailed patch information.
Likely exposure
Exposure is most likely where giflib 5.1.4, specifically gif2rgb, processes untrusted GIF files in batch jobs, web services, media pipelines, or automated converters. Systems that do not invoke gif2rgb are less directly exposed based on the supplied evidence.
Exploitation context
The CVE says remote attackers can trigger denial of service via a GIF-format file. CISA KEV status is false in the bundle, and no cited source here supports active exploitation in the wild.
Researcher notes
Evidence is sparse: the bundle names giflib 5.1.4 and gif2rgb, but omits CVSS, CWE, detailed affected ranges, and fixed versions. Validate exposure by tracing actual use of gif2rgb rather than assuming all giflib consumers are affected.
Mitigation direction
- Identify systems using giflib 5.1.4 or the gif2rgb utility.
- Restrict gif2rgb processing of untrusted GIF files where possible.
- Apply vendor or distribution guidance when an available fix is identified.
- Use memory and process limits around image conversion jobs.
- Monitor conversion services for abnormal memory growth or crashes.
Validation and detection
- Inventory installed giflib versions and packaged gif2rgb binaries.
- Confirm whether production workflows invoke gif2rgb on user-supplied GIFs.
- Review crash, OOM, and service restart logs around image conversion.
- Check vendor advisories or package changelogs for fixed giflib builds.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-40633 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://sourceforge.net/p/giflib/bugs/157/CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.