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Fencer Vulns
medium 5.5

CVE-2021-33294 json

In elfutils 0.183, an infinite loop was found in the function handle_symtab in readelf.c .Which allows attackers to cause a denial of servi…

published 2023-07-18 3 y ago modified 2026-10-14 25 d ago also EUVD-2021-20005

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 26%
public exploits
0
none known

Summary

In elfutils 0.183, an infinite loop was found in the function handle_symtab in readelf.c .Which allows attackers to cause a denial of service (infinite loop) via crafted file.

Patch / fix

  • 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
  • elfutils Debian 14, Debian 13, Debian 12 0.185-2

debian advisories DEBIAN-CVE-2021-33294

  • elfutils Ubuntu 20.04 LTS 0.176-1.1ubuntu0.1
  • elfutils Ubuntu Pro 14.04 LTS 0.158-0ubuntu5.3+esm1
  • elfutils Ubuntu Pro 16.04 LTS 0.165-3ubuntu1.2+esm1
  • elfutils Ubuntu Pro 18.04 LTS 0.170-0.4ubuntu0.1+esm1

ubuntu advisories UBUNTU-CVE-2021-33294

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

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-2021-33294 updated cvss 6.2

elfutils: an infinite loop was found in the function handle_symtab in readelf.c which causes denial of service

  • Red Hat Enterprise Linux 6 elfutils, elfutils-libs, elfutils-libelf Red Hat Enterprise Linux 7 elfutils, elfutils-libs, elfutils-libelf, elfutils-default-yama-scope
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 elfutils, elfutils-libs, elfutils-libelf, gcc-toolset-11-elfutils, elfutils-default-yama-scope, gcc-toolset-11-elfutils-libs, +2 more Red Hat Enterprise Linux 9 elfutils, elfutils-libs, elfutils-libelf, elfutils-debuginfod, elfutils-debuginfod-client, elfutils-default-yama-scope Red Hat Virtualization 4 elfutils
    not affected: vulnerable code not present

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 5.5

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 SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • sourceware.org https://sourceware.org/bugzilla/show_bug.cgi?id=27501 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

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-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.