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CVE-2026-54522

MessagePack for Ruby is an implementation of the MessagePack binary serialization format. Prior to 1.8.2, MessagePack::Buffer#clear in ext/msgpack/buffer.c leaves rmem_last, rmem_end, and rmem_owner stale after _msgpack_buffer_shift_chunk returns an rmem page to the shared pool, allowing a subsequent Buffer#write and a second MessagePack::Buffer to alias the page and disclose or corrupt cross-buffer data. This issue is fixed in version 1.8.2.
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:3e026383dda58a4a7124ff767b40a351ee2222891eaa0a59b5a8b1dd9258c4b2
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0

Affected products and versions

1 source assertion
{"product":"msgpack-ruby","vendor":"msgpack","versions":[{"status":"affected","version":"< 1.8.2"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:5641b0b9238d634c6132f0cbede0e0df6d805024dfbdd87ae7e86a1c404bac79 · sha256:beffaf7426956aee… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"LOCAL","baseScore":2.1,"baseSeverity":"LOW","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"NONE"},"metric_type":"cvssV4_0"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:5641b0b9238d634c6132f0cbede0e0df6d805024dfbdd87ae7e86a1c404bac79 · sha256:beffaf7426956aee… · /containers/cna/metrics/0/cvssV4_0

CWE assertions

1 source assertion
{"cweId":"CWE-416","description":"CWE-416: Use After Free","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:5641b0b9238d634c6132f0cbede0e0df6d805024dfbdd87ae7e86a1c404bac79 · sha256:beffaf7426956aee… · /containers/cna/problemTypes/0/descriptions/0

Source references

3 source assertions
{"name":"https://github.com/msgpack/msgpack-ruby/commit/5627d71606b565641d2dd501b82aae862f4abe90","tags":["x_refsource_MISC"],"url":"https://github.com/msgpack/msgpack-ruby/commit/5627d71606b565641d2dd501b82aae862f4abe90"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:5641b0b9238d634c6132f0cbede0e0df6d805024dfbdd87ae7e86a1c404bac79 · sha256:beffaf7426956aee… · /containers/cna/references/1
{"tags":["exploit"],"url":"https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:5641b0b9238d634c6132f0cbede0e0df6d805024dfbdd87ae7e86a1c404bac79 · sha256:beffaf7426956aee… · /containers/adp/0/references/0
{"name":"https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938","tags":["x_refsource_CONFIRM"],"url":"https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:5641b0b9238d634c6132f0cbede0e0df6d805024dfbdd87ae7e86a1c404bac79 · sha256:beffaf7426956aee… · /containers/cna/references/0

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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