CVE-2026-33487 goxmldsig has validateSignature Loop Variable Capture Signature Bypass
Attackers can bypass XML digital signature validation in goxmldsig due to a loop variable capture bug, allowing forged signatures to be accepted.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33487?
CVE-2026-33487 is a high-severity vulnerability in russellhaering goxmldsig, published on 26 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
goxmlsig provides XML Digital Signatures implemented in Go. Prior to version 1.6.0, the `validateSignature` function in `validate.go` goes through the references in the `SignedInfo` block to find one that matches the signed element's ID. In Go versions before 1.22, or when `go.mod` uses an older version, there is a loop variable capture issue. The code takes the address of the loop variable `_ref` instead of its value. As a result, if more than one reference matches the ID or if the loop logic is incorrect, the `ref` pointer will always end up pointing to the last element in the `SignedInfo.References` slice after the loop. goxmlsig version 1.6.0 contains a patch.
Which versions are affected by CVE-2026-33487?
3 open source packages ship an affected version, including github.com/russellhaering/goxmldsig. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/russellhaering/goxmldsig Go | All versions | 1.6.0 |
github.com/russellhaering/goxmldsig Go | All versions | 1.6.0 |
github.com/russellhaering/goxmldsig Go | All versions | 1.6.0 |
Products include Goxmldsig Project Goxmldsig.
How do I fix CVE-2026-33487?
Upgrade github.com/russellhaering/goxmldsig to 1.6.0 or later.
Is CVE-2026-33487 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33487 exists.
Other vulnerabilities in russellhaering goxmldsig
Sources
Also known as CLEANSTART-2026-TW34089, CLEANSTART-2026-VA24082, CLEANSTART-2026-WK71249, GHSA-479m-364c-43vc, GO-2026-4753, MINI-2h4j-p74g-qr9p and 24 more.