Security readout for executives and security teams
Plain-English summary
CVE-2026-28231 affects pillow_heif, a Python HEIF image library. Older versions can mishandle very large image dimensions during encoding, causing memory to be read outside intended bounds. Business impact is mainly possible data leakage into generated images or service crashes. Version 1.3.0 fixes the issue.
Executive priority
Treat as a targeted maintenance priority for image-processing systems. It is not documented as actively exploited, but it can affect confidentiality and availability in default configurations. Upgrade promptly where pillow_heif handles untrusted images.
Technical view
Before pillow_heif 1.3.0, an integer overflow in _pillow_heif.c encode-path buffer validation can bypass bounds checks. The result is a heap out-of-bounds read. The advisory lists CWE-125 and CWE-190, CVSS v4.0 score 5.5, network attack vector, low complexity, no privileges, and no user interaction.
Likely exposure
Exposure is most likely in Python applications using pillow_heif versions before 1.3.0 to encode HEIF images, especially services processing untrusted image content or dimensions. The source states no special configuration is required and default settings are affected.
Exploitation context
The source bundle does not indicate active exploitation, and KEV is false. The vulnerability can be triggered by large image dimensions in the encode path. Reported impacts are heap memory disclosure into encoded images or denial of service through process crash.
Researcher notes
Primary evidence is the GitHub Security Advisory, the fixing commit, and the v1.3.0 release. The bundle provides no CPE entries and no active-exploitation evidence. Analysis should focus on dependency reachability: whether vulnerable versions are installed and encode paths are reachable with attacker-controlled dimensions.
Mitigation direction
- Upgrade pillow_heif to version 1.3.0 or later.
- Prioritize internet-facing or automated image-processing services first.
- If upgrade is delayed, reduce exposure of HEIF encoding paths handling untrusted input.
- Review the GitHub advisory and release notes for vendor guidance.
Validation and detection
- Inventory Python dependencies for pillow_heif versions below 1.3.0.
- Identify applications that encode HEIF images using pillow_heif.
- Confirm deployed environments use pillow_heif 1.3.0 or later.
- Review service logs for unexplained crashes in image-processing workflows.
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 lookupCWE-190: 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-2026-28231 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
- 5.5 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
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:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
5.5MediumVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/bigcat88/pillow_heif/security/advisories/GHSA-5gjj-6r7v-ph3xCVE reference · x_refsource_CONFIRM
- https://github.com/bigcat88/pillow_heif/commit/8305a15d3780c533b762578cbe987d27a2c59c7aCVE reference · x_refsource_MISC
- https://github.com/bigcat88/pillow_heif/releases/tag/v1.3.0CVE 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.
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.
Integer Overflow or Wraparound
Integer Overflow or Wraparound represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.