CVE
AutoMapper denial of service via unbounded recursion in mapping
Affects AutoMapper before 15.1.4 and 16.0.0 through 16.2.x when deeply nested input is mapped into a constructor-built destination with a recursive member. Fixed in 15.1.4 and 16.3.0.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Exploited
- Proof of concept public, per CISA
- Fix
- Fixed in 16.3.0, 15.1.4
- Who is exposed
- Default setups
Do first: Check every install: default setups are affected.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.66% · 52nd percentile
- 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? →
- 58/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Default setups
- 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: poc
- Automatable: yes
- Technical impact: partial
Summary
AutoMapper, a .NET object-to-object mapping library from LuckyPennySoftware, can be made to crash when it maps deeply nested attacker-influenced input, because a recursion-depth check runs too late for certain constructor-based mappings. An attacker can trigger this remotely, without logging in, by sending that input, and the resulting stack overflow terminates the process.
Original description
AutoMapper is a convention-based object-object mapper in .NET. Prior to 15.1.4 and from 16.0.0 until 16.3.0, AutoMapper increments type depth only after creating the destination, so recursive mapping performed through constructor parameters occurs before MaxDepth is counted. Destinations built through positional records or other constructors, and recursive ConstructUsing mappings that call context.Mapper, can therefore bypass explicit MaxDepth values and the default limit of 64. Deep attacker-influenced input can throw an uncatchable StackOverflowException and terminate the process. This issue is fixed in versions 15.1.4 and 16.3.0.
Who should check
Teams running NuGet AutoMapper before 15.1.4 or 16.0.0 to 16.3.0 that map deep, attacker-influenced input into constructor-built or positional record types with a recursive member.
Not fixed by: Setting MaxDepth as recommended for CVE-2026-32933 doesn't protect these mappings.
“Any application that maps attacker-influenced, deeply nested data to a destination type built through a constructor, with a recursive member, can be crashed.”
cve.now Index
- Exploitation15/40CISA rates a proof of concept as public
- Exposure25/25Default setups, CISA rates it automatable
- Reach10/20Affects NuGet packages
- Severity7.5/10CVSS 7.5
- No patch0/5No signal
What would change the score
- Would score about 83 if added to CISA KEV
- Would score about 78 if CISA's SSVC rates exploitation active
What to do
Check every install: default setups are affected.
Upgrade to a fixed version: 16.3.0, 15.1.4.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-128082 (AutoMapper: Uncontrolled Recursion with Constructor Parameters), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-128082 (entry last updated 2026-11-13):
Affected:
- LuckyPennySoftware AutoMapper: from 16.0.0, fixed in 16.3.0; fixed in 15.1.4
- NuGet package AutoMapper: from 16.0.0, fixed in 16.3.0
- NuGet package AutoMapper: fixed in 15.1.4
Fixed versions: 16.3.0, 15.1.4.
Conditions (all must be true for the bug to be hit):
- Destination type is built through a constructor (such as a positional record) and its constructor parameters map recursively. (source: https://github.com/LuckyPennySoftware/AutoMapper/security/advisories/GHSA-6vhm-j9h7-f9gh)
- Destination type has a recursive member. (source: https://github.com/LuckyPennySoftware/AutoMapper/security/advisories/GHSA-6vhm-j9h7-f9gh)
- Mapping uses ConstructUsing that maps recursively through context.Mapper. (source: https://github.com/LuckyPennySoftware/AutoMapper/security/advisories/GHSA-6vhm-j9h7-f9gh)
Setup: the bug is reachable in a default setup; no special feature or setting is needed.
Attacker needs: network access, no login, no user action.
CISA KEV: CVE-2026-128082 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-128082 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Packages (NuGet): find every lockfile in each project and run the stack.check operation of the cve.now MCP server (execute) on each one. Compare the resolved versions, not the ranges a manifest declares, with the affected versions above. Include transitive dependencies.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/LuckyPennySoftware/AutoMapper/security/advisories/GHSA-6vhm-j9h7-f9gh
- https://github.com/LuckyPennySoftware/AutoMapper/commit/4d51a4b8125b4d2302f2f1f455747c9648ad1acb
- https://github.com/LuckyPennySoftware/AutoMapper/commit/639c2748cb9d3d07df8b86879ba7bcf211675c86
- https://github.com/LuckyPennySoftware/AutoMapper/releases/tag/v15.1.4
- https://github.com/LuckyPennySoftware/AutoMapper/releases/tag/v16.3.0
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-128082
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-128082"}.Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: poc · Automatable: yes · Technical impact: partial
- Record last updated
Affected versions
- LuckyPennySoftware AutoMapper
From 16.0.0 · fixed in 16.3.0; fixed in 15.1.4
- AutoMapperNuGet
From 16.0.0 · fixed in 16.3.0
Fixed in 16.3.0 (released Nov 5, 2026, 8 days before disclosure).
- AutoMapperNuGet
fixed in 15.1.4
Fixed in 15.1.4 (released Nov 5, 2026, 8 days before disclosure).
The latest release, 17.0.0, is not affected.
Evidence 7
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-128082
Is CVE-2026-128082 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. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
Deeply nested input can exhaust the stack during mapping, causing a StackOverflowException. That exception cannot be caught and terminates the process, which is a denial of service.Source: github.com
Which versions are affected by CVE-2026-128082?
AutoMapper: from 16.0.0 before 16.3.0; before 15.1.4. AutoMapper (NuGet): from 16.0.0 before 16.3.0. AutoMapper (NuGet): before 15.1.4.Source: cve.now feed data
Am I affected, and how do I check?
Affected versions are AutoMapper before 15.1.4 and 16.0.0 through 16.2.x. The issue applies when the destination type is built through a constructor, such as a positional record, has a recursive member, and its constructor parameters map recursively, or when ConstructUsing maps recursively through context.Mapper. The AutoMapper package version in a project file shows which version is in use.Source: github.com
How do I fix CVE-2026-128082?
Upgrade to AutoMapper 16.3.0 or 15.1.4, which are the fixed versions for this vulnerability.Source: github.com