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Response snapshot Oct 26, 2026, 23:07 UTC

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VulnerabilityCVE-2026-113729

Moov signedxml: Unauthenticated denial of service in exclusive XML canonicalization

Exclusive XML canonicalization (`http://www.w3.org/2001/10/xml-exc-c14n#`) in `github.com/moov-io/signedxml` copied the entire accumulated namespace map at every node during `ValidateReferences()`, before any reference digest or signature check.

Published Updated

At a glance

Exploited
Not known
Severity
7.5 High (CVSS 3.1)
Chance of exploitation
0.5% in the next 30 days
Sources
2 independent sources

What to do

GitHub lists first patched versions: github.com/moov-io/signedxml: 1.4.1. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-5588-rp99-5fjh (opens a new tab)

What happened

Exclusive XML canonicalization (`http://www.w3.org/2001/10/xml-exc-c14n#`) in `github.com/moov-io/signedxml` copied the entire accumulated namespace map at every node during `ValidateReferences()`, before any reference digest or signature check.

For a chain of nested elements that each declare many unused namespace prefixes, that produced **O(m × depth²)** time and peak memory (`m` = prefixes per level). `beevik/etree` caps tree depth (~1024), but `m` is unbounded, so a small attacker-controlled document (on the order of 1 MB) could drive multi-gigabyte allocations and OOM the process. No valid signature, matching certificate, or authentication is required.

This is the library’s core path for SAML / WS-Federation service providers, which canonicalize attacker-supplied XML prior to authentication.

### Affected

Continue reading

- Package: `github.com/moov-io/signedxml` - Function: `ExclusiveCanonicalization` (`exclusivecanonicalization.go`) - Verified: **v1.4.0** and current default branch (commit `d79064a`). Earlier v1.2.x–v1.3.x releases are likely affected.

### Remediation

Do not copy the whole namespace map per node. Maintain a single scope and push/pop only the prefixes introduced at each element. Replace linear prefix-in-scope scans with set lookups. Impose a defensive cap on in-scope namespace declarations and return an error rather than allocating unbounded memory.

From @shuji-oh ``` Thanks for the fix — I re-ran my PoC against this branch and confirmed the memory blowup is gone.

Before (main)

-- Doubling depth each time (m=10 fixed): allocated grows ~4x each time ≈ O(depth^2) -- depth=250 m=10 payload= 0.07MB allocated= 45MB depth=500 m=10 payload= 0.14MB allocated= 179MB depth=1000 m=10 payload= 0.27MB allocated= 711MB -- Increasing m (depth=1000 fixed): allocated scales roughly linearly with m -- depth=1000 m=5 payload= 0.16MB allocated= 377MB depth=1000 m=100 payload= 2.57MB allocated= 6278MB After (fix/exc-c14n-namespace-dos)

-- Doubling depth each time (m=10 fixed): allocated grows ~4x each time ≈ O(depth^2) -- depth=250 m=10 payload= 0.07MB allocated= 2MB depth=500 m=10 payload= 0.14MB allocated= 4MB depth=1000 m=10 payload= 0.27MB allocated= 7MB -- Increasing m (depth=1000 fixed): allocated scales roughly linearly with m -- depth=1000 m=5 payload= 0.16MB allocated= 4MB depth=1000 m=100 payload= 2.

57MB allocated= 47MB That's roughly a 100–130x reduction in peak allocation for the same payload sizes, and no OOM in any of my runs. This looks like it resolves the issue — thanks for the quick fix! ```

### Credit

Reported by Shuji Ohira ([@shuji-oh](https://github.com/shuji-oh)).

Affected package ranges reported by GitHub: github.com/moov-io/signedxml: <= 1.4.0

Scores and how they were measured

CVSS base severity

7.5

Version 3.1As of

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.5%

Scored Percentile 39.5%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-5588-rp99-5fjh (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-5588-rp99-5fjh, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-5588-rp99-5fjh, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  4. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-5588-rp99-5fjh, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  5. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-5588-rp99-5fjh, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  6. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-5588-rp99-5fjh, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  7. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-5588-rp99-5fjh, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  8. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-5588-rp99-5fjh, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  9. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-5588-rp99-5fjh, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  10. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-5588-rp99-5fjh, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  11. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-5588-rp99-5fjh, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  12. Primary source

    NVD CVE-2026-113729 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  13. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  14. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-113729, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 22). Moov signedxml: Unauthenticated denial of service in exclusive XML canonicalization (CVE-2026-113729). https://kevwire.com/record/CVE-2026-113729

MLA

"Moov signedxml: Unauthenticated denial of service in exclusive XML canonicalization (CVE-2026-113729)." KEVWire, 22 Oct. 2026, kevwire.com/record/CVE-2026-113729.

Chicago

KEVWire. "Moov signedxml: Unauthenticated denial of service in exclusive XML canonicalization (CVE-2026-113729)." Last modified October 22, 2026. https://kevwire.com/record/CVE-2026-113729.

Evidence summary (plain text)

Moov signedxml: Unauthenticated denial of service in exclusive XML canonicalization (Oct 21, 2026).
Exclusive XML canonicalization (`http://www.w3.org/2001/10/xml-exc-c14n#`) in `github.com/moov-io/signedxml` copied the entire accumulated namespace map at every node during `ValidateReferences()`, before any reference digest or signature check.

For a chain of nested elements that each declare many unused namespace prefixes, that produced **O(m × depth²)** time and peak memory (`m` = prefixes per level). `beevik/etree` caps tree depth (~1024), but `m` is unbounded, so a small attacker-controlled document (on the order of 1 MB) could drive multi-gigabyte allocations and OOM the process. No valid signature, matching certificate, or authentication is required.
CVSS 7.5 (version 3.1; evidence as of Oct 22, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-113729).
EPSS 0.5% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-113729&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-5588-rp99-5fjh: https://github.com/advisories/GHSA-5588-rp99-5fjh
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQxNTo1Mjo1NlrOAAfxiA%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQxNDowNjoxNFrOAAfxZw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQwODoyNzoyM1rOAAYp9A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozNTo1OFrOAAfwCQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozMDoxM1rOAAfv2A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyODowOVrOAAfv1g%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyNDoyMFrOAAfv1Q%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDo0NTowN1rOAAfvzQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDozMDoyNlrOAAfvxw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDowMzo1N1rOAAfvxQ%3D%3D
NVD CVE-2026-113729: https://nvd.nist.gov/vuln/detail/CVE-2026-113729
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?pubStartDate=2026-10-12T13:35:55.142Z&pubEndDate=2026-10-26T13:35:55.142Z&resultsPerPage=500&startIndex=7000
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-113729&date=2026-10-26
Record ID: CVE-2026-113729.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 26, 2026, 19:40 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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