CVE-2026-103636: high-severity vulnerability in Apache DataSketches
Apache DataSketches: datasketches-cpp: Out-of-bounds read in VarOpt union deserialization allows denial of service via a truncated sketch
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.4%
Out-of-bounds read in the VarOpt union deserialization of Apache DataSketches C++ (repo: datasketches-cpp).
var_opt_union::deserialize() read the 32-byte preamble of a non-empty union after checking that only 8 bytes were available, so a truncated serialized union could cause a read of up to 24 bytes past the end of the input. For such inputs, the size remaining for the embedded sketch was also computed by an unsigned subtraction that could wrap around, so the embedded sketch's own size checks no longer limited reads to the input. The bytes read can become part of the deserialized union's state. This can cause a crash (denial of service) and could expose adjacent memory contents.
This issue affects Apache DataSketches C++: from 2.0.0-incubating before 5.3.0. Only applications that deserialize VarOpt unions from untrusted sources are affected.
Users are recommended to upgrade to version 5.3.0, which fixes this issue.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
Apache Software Foundation · Apache DataSketchesRelated CVEs — Apache DataSketches
In the same product, most dangerous first.
CVE-2026-103501CRITICALApache DataSketches: datasketches-cpp: HLL CouponList Deserialization Buffer Overflow allows memory corruption via a crafted sketchEPSS 0.6%CVE-2026-103634MEDIUMApache DataSketches: datasketches-cpp: Out-of-bounds read and write in Count-Min sketch deserialization allows memory corruption via a crafted sketchEPSS 0.5%CVE-2026-103635CRITICALApache DataSketches: datasketches-cpp: Out-of-bounds read in compact Theta sketch deserialization allows denial of service via a crafted sketchEPSS 0.4%CVE-2026-103513CRITICALApache DataSketches: datasketches-cpp: Out-of-bounds read and write in the CPC sketch deserialization allows memory corruption via a crafted sketchEPSS 0.4%