Security readout for executives and security teams
Plain-English summary
LibGD image library through 2.3.2 can read outside expected memory bounds when buffer operations fail and return values are not checked. Business impact is mainly service disruption in software that processes images through LibGD; the CVSS vector rates availability impact as high.
Executive priority
Schedule remediation in normal vulnerability patch cycles, with faster handling for Internet-facing image upload, conversion, or thumbnailing services. The main business risk is avoidable outage, not data theft, based on the supplied CVSS and references.
Technical view
CVE-2021-40812 is a CWE-125 out-of-bounds read in GD Graphics Library caused by missing gdGetBuf and gdPutBuf return-value checks. The CVSS 3.1 vector is AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H, indicating low-complexity network reachability with user interaction and availability-only impact.
Likely exposure
Exposure is most likely where applications, web services, or batch jobs use LibGD/libgd2 to parse or transform image content, especially content supplied by users or external systems. The bundle names LibGD through 2.3.2 and Debian's libgd2 update.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The CVSS vector requires user interaction and does not indicate confidentiality or integrity impact. Treat it as a denial-of-service risk until vendor-specific evidence says otherwise.
Researcher notes
Evidence is limited to the CVE record, upstream issue/commit references, and a Debian LTS advisory. The affected range is described as LibGD through 2.3.2, but the bundle does not provide a universal fixed release number across all packaging ecosystems.
Mitigation direction
- Inventory systems and containers for LibGD or libgd2 versions through 2.3.2.
- Apply vendor or distribution security updates that address CVE-2021-40812.
- For source builds, review the upstream fixing commit and vendor guidance before rebuilding.
- Prioritize services that process externally supplied images.
- Reduce exposure of image-processing paths until patched, where operationally feasible.
Validation and detection
- Confirm package metadata or SBOM entries no longer show vulnerable LibGD versions.
- Verify vendor changelogs mention CVE-2021-40812 or the referenced LibGD fix.
- Check image-processing services for recent crash or availability incidents.
- Confirm externally reachable upload or conversion paths run on patched hosts.
- Document any remaining embedded or statically linked LibGD copies.
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.
CWE-125: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-40812 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
- Medium
- CVSS
- 6.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
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 vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H2.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.5MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/libgd/libgd/commit/6f5136821be86e7068fcdf651ae9420b5d42e9a9CVE reference
- https://github.com/libgd/libgd/issues/750#issuecomment-914872385CVE reference
- [debian-lts-announce] 20240406 [SECURITY] [DLA 3781-1] libgd2 security updateCVE reference · mailing-list
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.
Out-of-bounds Read
Out-of-bounds Read represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.