CVE-2026-103635: Apache DataSketches: datasketches-cpp: Out-of-bounds read in compact Theta sketch deserialization allows denial of service via a crafted sketch
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 0.4%
Down from 0.6% on .
EPSS score, percentile 33.5 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 9.1 Critical
CVSS v3.1 base score, from CISA's enrichment of the record
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
- Which versions are affected?
Affected
- 3.1.0 through 5.2.0
Source: CISA KEV 2026.10.29, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
What to do
Advisories and patches
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 3.1.0 through 5.2.0 |
Versions not listed are: unaffected.
Source: CVE List, as of . About the data.
About this vulnerability
Out-of-bounds read in the compact Theta sketch deserialization of Apache DataSketches C++ (repo: datasketches-cpp). compact_theta_sketch::deserialize() and wrapped_compact_theta_sketch::wrap() read header fields before checking that the input was long enough. For the compressed format, the size check could be defeated by a 32-bit overflow, and two header fields that control decoding were not val…
Summary: CVE record, as of .
- CISA has not added CVE-2026-103635 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
- The CVE record was published on 10 Oct 2026.
- The CVE record carries a CVSS v3.1 base score of 9.1 (Critical), taken from CISA's enrichment of the record.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.4% (percentile 33.5), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
- CISA's SSVC assessment in the CVE record: exploitation none, automatable yes, technical impact partial.
Source: CISA KEV 2026.10.29, as of ; CVE List, as of ; FIRST EPSS, as of . About the data.
Description
Apache DataSketches: datasketches-cpp: Out-of-bounds read in compact Theta sketch deserialization allows denial of service via a crafted sketch
Out-of-bounds read in the compact Theta sketch deserialization of Apache DataSketches C++ (repo: datasketches-cpp). compact_theta_sketch::deserialize() and wrapped_compact_theta_sketch::wrap() read header fields before checking that the input was long enough. For the compressed format, the size check could be defeated by a 32-bit overflow, and two header fields that control decoding were not validated; this also affected deserialization from a stream. A crafted or truncated sketch could cause a read past the end of the input. In the compressed case the over-read can be large, and the bytes read can become part of the deserialized sketch. This can cause a crash (denial of service) and could expose adjacent memory contents. This issue affects Apache DataSketches C++: from 3.1.0 before 5.3.0. Only applications that deserialize Theta sketches from untrusted sources are affected. Users are recommended to upgrade to version 5.3.0, which fixes this issue.
Source: CVE List, as of . About the data.
Weakness
CWE-125, CWE-190
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |
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