Process memory exhaustion via rejected Punycode labels
Published Sep 22, 2026 · Updated Sep 22, 2026
Memory leak in Paul Johnson Net::IDN::Punycode 2.302 through 2.589 allows attackers to exhaust process memory via invalid labels. The XS decode_punycode path allocates a return scalar at twice the input length before validation, then rejection exceptions bypass its release. Only XS-backend callers processing attacker-controlled labels are exposed; repeated rejections grow memory until the embedding service is interrupted.
Summary
What happened
Memory leak in Paul Johnson Net::IDN::Punycode 2.302 through 2.589 allows attackers to exhaust process memory via invalid labels. The XS decode_punycode path allocates a return scalar at twice the input length before validation, then rejection exceptions bypass its release. Only XS-backend callers processing attacker-controlled labels are exposed; repeated rejections grow memory until the embedding service is interrupted.
The record
- CVE
- CVE-2026-87078
- Published
- Sep 22, 2026
- Updated
- Sep 22, 2026
- Vendor
- Paul Johnson
- Product
- Net::IDN::Punycode
- Classifications
- T1499
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Sep 22, 2026CVE publishedPublication date reported by the CVE source.
- Sep 22, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=2.302 <2.590
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Get started to see how Hinoki identifies affected software and validates exploitability in your environment.
Get started