# CVE-2026-9487: XML::Sig versions before 0.71 for Perl allow signature wrapping via duplicate ID

> Attackers can bypass XML signature verification in Perl applications by using duplicate IDs, potentially controlling SAML assertions.

- **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-wqp7-2ww4-q6mf

## What is CVE-2026-9487?

CVE-2026-9487 is a critical 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 signature wrapping via duplicate ID.

_get_signed_xml() in lib/XML/Sig.pm, called from verify(), resolves the SignedInfo Reference/@URI to a node with the XPath expression "//*[@ID='$id']" and returns the first node of the resulting node set. A document in which two elements share that ID value is accepted: the digest and signature are checked against whichever element comes first in document order, and the duplicate is not detected.

Such a document verifies successfully while an application that resolves the same ID independently can read the second, attacker supplied element; in a SAML2 context this places the contents of an Assertion under attacker control.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2026-9487?

It affects 1 product.


Products: Xml\ \.

## How do I fix CVE-2026-9487?

No fix has been published for CVE-2026-9487 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-9487 being exploited?

There is no known exploitation of CVE-2026-9487 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-2026-9390](https://insights.sbomify.com/CVE-2026-9390/): XML::Sig versions before 0.71 for Perl allow XPath injection in ID lookup (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-2026-9487 and fix it if it is affected.

What it is: CVE-2026-9487 is a critical 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-2026-9487 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-2026-9487/ (Markdown: https://insights.sbomify.com/CVE-2026-9487/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-9487
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-9487
- OSV: https://osv.dev/vulnerability/CVE-2026-9487

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-9487/
Summaries are generated and may contain mistakes; the official description above is the record.