CVE-2026-40345

highpriority · track · 10EPSS 0.005 · 44 %ileexploit · PoCDEUS
grimoire priorityP1 · Urgent
Exploitable?
Public exploit
1 exploit · PoC
Likely / severe?
0.52% (44th) EPSS
CVSS 8.2 · high
Is it mine?
3 products
Check your exposure
Who says so?
2 sources
cert_bund · osv

EPSS · scored 2026-10-27

deepmerge-ts is a typescript library providing functionality to deep merging of javascript objects. Prior to 8.0.0, the deepmerge, deepmergeCustom, deepmergeInto, and deepmergeIntoCustom APIs do not track visited objects or object pairs when recursively merging records. When two input values contain self-references at the same property path, the merge logic repeatedly revisits the same pair until Node.js raises RangeError: Maximum call stack size exceeded. Applications that merge attacker-controlled recursive object graphs can synchronously crash the affected process or cause repeated worker restarts. Plain JSON input alone cannot create the recursive graph required to trigger the issue. This issue is fixed in version 8.0.0.

01

cvss

Technical severity, 0–10. One row per scoring source.

8.2
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.9–8.2

v4.08.2highCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Xsecondary · security-advisories@github.com
v4.06.9mediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Xsecondary · CVSS-BT (t0sche)
02

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: no · Technical Impact: partialcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

04

exploits (1)

Public proof-of-concept and weaponised exploit code.

05

affected products (3)

Products and version ranges known to be affected.

06

advisories (2)

Vendor and ecosystem advisories describing this.

  • WID-SEC-W-2026-3831IBM App Connect Enterprise: Mehrere SchwachstellenDeutsch2026-10-08csaf · cert_bundDE

    Ein Angreifer kann mehrere Schwachstellen in IBM App Connect Enterprise ausnutzen, um Sicherheitsvorkehrungen zu umgehen, um einen Denial of Service Angriff durchzuführen, und um Informationen offenzulegen.

  • GHSA-ggr8-5vv4-36mxDeepmergeTS has stack exhaustion when merging recursive object graphs2026-08-17ghsa · osvUS

    ### Summary `deepmerge()` and `deepmergeInto()` can be crashed with a crafted recursive object graph. When both merged values contain self-references at the same property path, the library recurses until Node throws `RangeError: Maximum call stack size exceeded`. ### Details Record merging is implemented recursively. For each enumerable key, the library collects the values from every input object and immediately calls the same merge routine on that property. There is no visited-object tracking, pair tracking, or cycle detection in that recursion. As a result, if two merged records both point back to themselves through the same key path, the merge logic keeps revisiting the same object pair forever. This is reachable through the real public API: * `deepmerge(...)` * `deepmergeCustom(...)(...)` * `deepmergeInto(target, ...)` * `deepmergeIntoCustom(...)(target, ...)` The issue only occurs when recursive object graphs are supplied. Plain JSON alone does not create this condition. ### PoC ```js import { deepmerge, deepmergeInto } from "deepmerge-ts"; const left = {}; left.self = left; const right = {}; right.self = right; try { deepmerge(left, right); } catch (error) { console.log(error.name, error.message); // Expected: the merge should reject or safely handle recursive input without exhausting the stack. // Vulnerable behavior: RangeError Maximum call stack size exceeded } const target = {}; target.self = target; const source = {}; source.self = source; try { deepmergeInto(target, source); } catch (error) { console.log(error.name, error.message); // Expected: the merge should reject or safely handle recursive input without exhausting the stack. // Vulnerable behavior: RangeError Maximum call stack size exceeded } ``` ### Impact Applications that pass attacker-controlled recursive object graphs into these APIs can be forced into a synchronous crash path. In Node.js services, that can terminate request handling for the affected process or trigger repeated worker restarts until the malicious input is blocked.

07

sources

Which sources assert this record, and when.

published 2026-08-20modified 2026-10-18
08

references (4) nvd

External citations — patches, advisories, analysis.

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