CVE-2026-55211 is a critical-severity (CVSS 9.8) Out-of-bounds Read vulnerability in surfio. A fix is available for surfio — see the affected versions and patch details below.
surfio IRAP header size fields cause out-of-bounds reads
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-55211.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-55211 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 382,574 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
surfioReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Surfio is a library for reading and writing surface files. Prior to 0.0.19, surfio does not correctly validate size fields in IRAP files, leading to a buffer overflow when untrusted files are parsed. The severity assumes surfio is used to parse untrusted files in a networking context such as a web service. This issue is fixed in version 0.0.19.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | surfio | all versions | 0.0.19pip install --upgrade 'surfio==0.0.19' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for surfio, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update surfio to 0.0.19 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55211 is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.
Frequently Asked Questions
Is CVE-2026-55211 in your dependencies?
Find it across PyPI, including transitive dependencies.