stellar-xdr's StringM::from_str bypasses max length validation

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-29795: 0.22% estimated exploitation activity in the next 30 days; percentile 13.10 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact StringM::fromstr does not validate that the input length is within the declared maximum (MAX). Calling StringM::<N::fromstr(s) where s is longer than N bytes succeeds and returns an Ok value instead of Err(Error::LengthExceedsMax), producing a StringM that violates its length invariant. This affects any code that constructs StringM values from string input using FromStr (including str::parse), and relies on the type's maximum length constraint being enforced. An oversized StringM could propagate through serialization, validation, or other logic that assumes the invariant holds. All published versions of the stellar-xdr crate up to and including v25.0.0 are affected. Patches The fix is merged in #500. It replaces the direct Ok(Self(b)) construction with b.tryinto(), which routes through TryFrom<Vec<u8 and properly validates the length — matching the pattern already used by BytesM::fromstr. Users should upgrade to the first release containing this fix once published (the next…

Published by the source

5 Mar 2026, 20:45 UTC

Last modified by the source

6 Mar 2026, 22:51 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-x57h-xx53-v53w

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# Patch Next advisory brief: CVE-2026-29795

Advisory: stellar-xdr's StringM::from_str bypasses max length validation
IDs: CVE-2026-29795, GHSA-x57h-xx53-v53w
Record: https://patchnext.com/advisories/cve-2026-29795 (revision 1, source checked 26 Oct 2026, 15:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: stellar-xdr 25.0.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io stellar-xdr: affected <= 25.0.0; fixed in 25.0.1

## Suggested inspection (read-only)
- crates.io stellar-xdr: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on stellar-xdr.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-x57h-xx53-v53w (GitHub-reviewed advisory GHSA-x57h-xx53-v53w lists affected ranges: crates.io stellar-xdr >=0 <=25.0.0)

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