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

Status: published. Published: 2026-10-16. Updated: 2026-11-06.

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.

## Remediation

- workaround: To mitigate this issue, avoid configuring applications that use `pmap_getmaps()` to query untrusted or attacker-controlled portmapper services. If such functionality is essential, restrict network access for services utilizing `pmap_getmaps()` to only trusted hosts via firewall rules. Additionally, consider isolating client applications that call `pmap_getmaps()` into constrained environments to limit the impact of potential resource exhaustion. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Hardened Images (libtirpc-main): ≥ 1.3.8-0.1.hum1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (libtirpc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (libtirpc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (libtirpc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (libtirpc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (libtirpc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-8): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 5 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 5.3 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.42% as of 2026-11-05; percentile 36.52%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-1050

## Exploit evidence

- exploit: https://bugzilla.redhat.com/show_bug.cgi?id=2478979 (ADP: CISA-ADP)

## References

- https://access.redhat.com/errata/RHSA-2026:80360 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-85977 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2478979 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2478979 (ADP: CISA-ADP; exploit)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-85977; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-85977; retrieved 2026-11-06; source updated Not reported

Revision: 66aa97f094790af5ef891c5f252903294e5b6d2def83be0724c47468d376bb0b

Canonical: https://y2.dev/cve/CVE-2026-85977

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