CVE-2026-29795: stellar-xdr: `StringM::from_str` bypasses max length validation

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-06 · updated 2026-06-17
Weakness: CWE-770

Description

stellar-xdr is a library and CLI containing types and functionality for working with Stellar XDR. Prior to version 25.0.1, StringM::from_str does not validate that the input length is within the declared maximum (MAX). Calling StringM::<N>::from_str(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. This issue has been patched in version 25.0.1.

Affected products

stellar rs-stellar-xdr: before 25.0.1 — fixed in 25.0.1

How to fix

Upgrade to a fixed version: stellar rs-stellar-xdr 25.0.1. Check the vendor advisory for mitigations.

References

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