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Fencer Vulns
high 7.5

CVE-2021-46828 json

In libtirpc before 1.3.3rc1, remote attackers could exhaust the file descriptors of a process that uses libtirpc because idle TCP connectio…

published 2022-07-20 4 y ago modified 2026-10-14 26 d ago also EUVD-2021-33483 , JLSEC-2026-1289

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
3.2%
EPSS 3.2% chance of exploitation in 30 days, percentile 88%
public exploits
0
none known

Summary

In libtirpc before 1.3.3rc1, remote attackers could exhaust the file descriptors of a process that uses libtirpc because idle TCP connections are mishandled. This can, in turn, lead to an svc_run infinite loop without accepting new connections.

Patch / fix

  • julia libtirpc_jll 1.3.7+0
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • libtirpc Debian 14, Debian 13, Debian 12 1.3.2-2.1

debian advisories DEBIAN-CVE-2021-46828

  • libtirpc Ubuntu 20.04 LTS 1.2.5-1ubuntu0.1
  • libtirpc Ubuntu 22.04 LTS 1.3.2-2ubuntu0.1

ubuntu advisories UBUNTU-CVE-2021-46828

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libtirpc RHEL 9 1.3.3-0.el9
  • libtirpc RHEL 8 1.1.4-6.el8

red hat advisories RHSA-2022:8400RHBA-2022:2065

  • libtirpc SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES 12 SP5 +6 more 1.0.1-17.24.1
  • libtirpc SLE Module for Basesystem 15 SP4, SLE Module for Basesystem 15 SP3, SLE Micro 5.2 +4 more 1.2.6-150300.3.14.1
  • libtirpc SLES for SAP 15 SP2, SLES for SAP 15 SP1, SLES for SAP 15 +16 more 1.0.2-150000.3.18.1

suse advisories SUSE-SU-2022:3791-1SUSE-SU-2022:3305-1SUSE-SU-2022:2991-1

  • libtirpc AlmaLinux 9 1.3.3-0.el9

almalinux advisories ALSA-2022:8400

  • libtirpc Rocky Linux 9 1.3.3-0.el9

rocky linux advisories RLSA-2022:8400

  • libtirpc Alpine 3.13 1.3.1-r1
  • libtirpc Alpine 3.16, Alpine 3.15, Alpine 3.14 1.3.2-r1
  • libtirpc Alpine 3.24, Alpine 3.23, Alpine 3.22 +5 more 1.3.2-r2

alpine advisories ALPINE-CVE-2021-46828

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-46828 updated cvss 7.5

libtirpc: DoS vulnerability with lots of connections

  • Red Hat Enterprise Linux 6 libtirpc Red Hat Enterprise Linux 7 libtirpc
    affected: no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder (v. 9) libtirpc-devel 1.3.3-0.el9, libtirpc-debuginfo 1.3.3-0.el9, libtirpc-debugsource 1.3.3-0.el9
    fixed: vendor fix RHSA-2022:8400
  • Red Hat Enterprise Linux BaseOS (v. 8) libtirpc 1.1.4-6.el8
    fixed: vendor fix RHBA-2022:2065
  • Red Hat Enterprise Linux BaseOS (v. 9) libtirpc 1.3.3-0.el9
    fixed: vendor fix RHSA-2022:8400

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-23-348-10 updated cvss 7.5

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

cisa ICSA-23-103-09 updated cvss 7.5

Siemens SCALANCE XCM332

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

cisa ICSA-23-194-04 updated cvss 7.5

Siemens SIMATIC MV500 Devices

  • Siemens SIMATIC MV540 H (6GF3540-0GE10) <V3.3.4 Siemens SIMATIC MV540 S (6GF3540-0CD10) <V3.3.4 Siemens SIMATIC MV550 H (6GF3550-0GE10) <V3.3.4 Siemens SIMATIC MV550 S (6GF3550-0CD10) <V3.3.4 Siemens SIMATIC MV560 U (6GF3560-0LE10) <V3.3.4 Siemens SIMATIC MV560 X (6GF3560-0HE10) <V3.3.4
    affected: fixed in V3.3.4 support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
18 mo ago

Exploit prediction

3.20% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
julia libtirpc_jll
<1.3.7+0
1.3.7+0

Affected products

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
  • CWE-755 Improper Handling of Exceptional Conditions
  • CWE-835 Loop with Unreachable Exit Condition

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.