# CVE-2026-85977: Libtirpc: libtirpc: denial of service via unbounded memory allocation during portmapper response decoding

> A remote attacker can cause a denial of service in applications using libtirpc by sending crafted portmapper responses that trigger unbounded memory allocation.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 16 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-85977, DEBIAN-CVE-2026-85977, ECHO-8a89-e7cc-2f31, GHSA-vc3g-5238-rmmw, RHSA-2026:80360, UBUNTU-CVE-2026-85977

## What is CVE-2026-85977?

CVE-2026-85977 is a medium-severity denial of service vulnerability in Red Hat Enterprise Linux 10, published on 16 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A flaw was found in libtirpc. A remote attacker can exploit this vulnerability by sending specially crafted PMAPPROC_DUMP replies to a client application that uses the pmap_getmaps() function against an attacker-controlled host. This unbounded decoding can lead to excessive memory and CPU allocation, causing the client process to experience a Denial of Service (DoS) due to resource exhaustion.

Weakness: CWE-1050 (Excessive Platform Resource Consumption within a Loop)

## Which versions are affected by CVE-2026-85977?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libtirpc` | Red Hat:hummingbird:1 | All versions | 0:1.3.8-0.1.hum1 |
| `libtirpc-devel` | Red Hat:hummingbird:1 | All versions | 0:1.3.8-0.1.hum1 |

## How do I fix CVE-2026-85977?

Apply the vendor's patch.

## Is CVE-2026-85977 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-85977 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-85977 and fix it if it is affected.

What it is: CVE-2026-85977 is a medium-severity denial of service vulnerability in Red Hat Enterprise Linux 10, published on 16 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-85977 exists.

Affected product: Red Hat Enterprise Linux 10. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-85977/ (Markdown: https://insights.sbomify.com/CVE-2026-85977/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-85977
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-85977
- OSV: https://osv.dev/vulnerability/CVE-2026-85977

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-85977/
Summaries are generated and may contain mistakes; the official description above is the record.