# CVE-2026-9390: XML::Sig versions before 0.71 for Perl allow XPath injection in ID lookup

> Attackers can inject XPath expressions to bypass XML signature verification, allowing them to validate malicious documents as legitimate.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Aug 2026
- **Updated:** 3 Aug 2026
- **Also known as:** GHSA-mhmm-7px6-jx3j

## What is CVE-2026-9390?

CVE-2026-9390 is a critical code injection vulnerability in TIMLEGGE XML::Sig, published on 3 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

XML::Sig versions before 0.71 for Perl allow XPath injection in ID lookup.

verify() and _get_signed_xml() in lib/XML/Sig.pm build XPath expressions by concatenating the SignedInfo/Reference/@URI value read from the document being verified. The value is neither escaped nor checked against the NCName grammar that XML requires of an ID, so a URI containing a single quote closes the string literal in the generated expression and appends arbitrary XPath operators.

A crafted URI can make the lookup match elements the reference does not name, or every element in the document, so which node is selected for digest verification is decided by the injected expression rather than by the reference.

Weakness: CWE-643 (Improper Neutralization of Data within XPath Expressions), CWE-1287 (Improper Validation of Specified Type of Input)

## Which versions are affected by CVE-2026-9390?

It affects 1 product.


Products: Xml\ \.

## How do I fix CVE-2026-9390?

No fix has been published for CVE-2026-9390 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-9390 being exploited?

There is no known exploitation of CVE-2026-9390 in the wild and no public exploit code.

## Other vulnerabilities in TIMLEGGE XML::Sig

- [CVE-2025-40934](https://insights.sbomify.com/CVE-2025-40934/): XML-Sig prior to 0.68 for Perl improperly validates XML without signatures (critical 9.3)
- [CVE-2026-9487](https://insights.sbomify.com/CVE-2026-9487/): XML::Sig versions before 0.71 for Perl allow signature wrapping via duplicate ID (critical 9.1)
- [CVE-2026-18568](https://insights.sbomify.com/CVE-2026-18568/): Security feature bypass in XML::Sig (high 7.5)
- [CVE-2012-1102](https://insights.sbomify.com/CVE-2012-1102/): XML external entity in perl-xml-atom (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-9390 and fix it if it is affected.

What it is: CVE-2026-9390 is a critical code injection vulnerability in TIMLEGGE XML::Sig, published on 3 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-9390 in the wild and no public exploit code.

Affected product: TIMLEGGE XML::Sig. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-9390/ (Markdown: https://insights.sbomify.com/CVE-2026-9390/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-9390
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-9390
- OSV: https://osv.dev/vulnerability/CVE-2026-9390

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-9390/
Summaries are generated and may contain mistakes; the official description above is the record.