CVE-2026-9521: fraillt bitsery

fraillt bitsery std_smart_ptr.h loadFromSharedState improper validation of specified type of input

CVSS 6.3 MediumEPSS 0.0040 · 34th percentile

Published by the CVE Program (CNA: VulDB) at 26 May 2026, 02:00 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
fraillt	bitsery	affected 5.2.0 affected 5.2.1 affected 5.2.2 affected 5.2.3 affected 5.2.4 unaffected 5.2.5

Identifiers

CVE-2026-9521

CNA

VulDB

Weakness (CWE)

CWE-20 · CWE-1287

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
6.3	Medium	4.0	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P	CNA (VulDB)Used for this record
7.3	High	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C	CNA (VulDB)
7.3	High	3.0	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C	CNA (VulDB)
7.5	High	2.0	AV:N/AC:L/Au:N/C:P/I:P/A:P/E:POC/RL:OF/RC:C	CNA (VulDB)

CISA KEV Not listed.
EPSS 0.0040, the 34th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 26 May 2026. New records show when each source confirmed them.

Sources

References from the CNA

vuldb.com/vuln/365541 vdb-entrytechnical-description
vuldb.com/vuln/365541/cti signaturepermissions-required
vuldb.com/submit/814457 third-party-advisory
github.com/fraillt/bitsery/blob/master/CHANGELOG.md#525-2025-10-09 release-notes
github.com/fraillt/bitsery/commit/66d16516e24893bebc1c8af52bf2fe9ad0735061 patch
github.com/fraillt/bitsery/releases/tag/v5.2.5 patch
github.com/fraillt/bitsery/ product
gist.github.com/TrebledJ/750abc64a826f19dd2d6774724629b71 exploit

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.