CVE-2026-77354Disclosure

LOWCVSS 8.7 · HIGH

Exploit discussion active in current signal (1 latest mentions)

Immediate actions

Patch affected systems immediately
Hunt for exploitation attempts and persistence artifacts

Recommended action window: High priority (within 72h)

NVD description

kin-openapi is a Go project for handling OpenAPI files. From 0.124.0 until 0.142.0, openapi3filter.sliceMapToSlice in openapi3filter/req_resp_decoder.go converts attacker-controlled sparse indexes from a deepObject query parameter into a dense slice by allocating entries from zero through the largest supplied index, after which buildResObj creates another slice of the same length. This allocation occurs before schema validation, so maxItems does not prevent it. An unauthenticated client can send a small query such as param[items][50000000]=x to an endpoint whose deepObject schema contains an array, forcing multi-gigabyte heap allocation and causing an OOM kill or restart loop. Other request-body encodings and styled parameters that do not produce bracketed integer indexes are not affected. This issue is fixed in version 0.142.0.

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2.5/ 10 priority

Sources & remediation

Other references

Weakness type (CWE)

CWE-400CWE-789

Priority

LOW

Exploitation

NONE

PoC

NONE

Patch

AVAILABLE

Momentum

NONE

Threat summary

Exploit tooling references are present in monitored signal
Patch or workaround signal is available
1 mentions across 1 observed day

What's happening

Exploit tool or code specified in 1 signal
Patch or workaround mentioned in 1 signal
Technical details provided in 1 signal
Disclosure: 1 classified signal
1 total mentions across 1 day

Deep dive

Activity timeline1 mentions / 1d

Signal classification1 categories

Disclosure

1100.0%

Referenced assets1 URL

By indicator

http://github.com/getkin/kin-openapi

Full discourse1 post

Upwind Security MDR@UpwindMDR45d
Disclosure
🚨High - kin-openapi deepObject Sparse Index OOM DoS (CVE-2026-77354) In http://github.com/getkin/kin-openapi, deepObject query decoding expands attacker-supplied sparse array indexes into dense slices before schema validation. A request like param[items][50000000]=x can trigger multi-GB heap allocation, leading to OOM kills/restart loops. 👉Affected: http://github.com/getkin/kin-openapi 0.124.0-0.141.x | Upgrade to 0.142.0
Post summary
This tweet discloses a high‑severity OOM DoS vulnerability in kin‑openapi’s deepObject parsing, explains how an attacker can trigger it, and advises upgrading to version 0.142.0 for remediation.
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