Silent element-count truncation via 32-bit bit-length overflow in packed-bit vector views
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Not reported
- Exploitation0/40No signal
- Exposure17/25No login or user action needed per the CVSS vector, reachable over the network without a login · Data gap: No advisory context yet
- Reach?/20Reach: unknown (data gap). No tracked technology or package matched
- Severity6.3/10CVSS 6.3
- No patch5/5No patch listed yet
What would change the score
- Would score about 73 if added to CISA KEV
- Would score about 68 if CISA's SSVC rates exploitation active
- Would score about 33 if advisories confirm default setups are exposed
CVE-2026-120954 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.3 (medium) and affects C Driver; no fixed version is listed yet.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 28/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
The BSON library's parser for its packed-bit binary vector data type is affected, particularly in builds for 32-bit platforms. An application that parses untrusted BSON input can silently process only a small part of the supplied elements while reporting success, so its results can be incorrect, though memory safety and confidentiality are not impacted.
Read the original description
A weakness in the BSON library's handling of a specialized binary vector data type allows an arithmetic wraparound when computing the number of elements described by an oversized attacker-supplied value. On builds where the platform word size is 32 bits, an application that parses untrusted BSON data can be made to process only a small fraction of the supplied elements while the operation reports success, producing results that disagree with byte-oriented accessors and with 64-bit builds of the same library. No authentication or user interaction is required beyond getting the application to parse the data. The impact is limited to data integrity; memory safety is not affected and no information is disclosed.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- MongoDB C Driver
From 2.0.0 · through 2.5.7
Evidence 1
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-120954
Is CVE-2026-120954 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-120954?
C Driver: from 2.0.0 through 2.5.7.Source: cve.now feed data