Description
The resolveImplicitLevels function in common/ubidi.c in the Unicode Bidirectional Algorithm implementation in ICU4C in International Components for Unicode (ICU) before 55.1 does not properly track directionally isolated pieces of text, which allows remote attackers to cause a denial of service (heap-based buffer overflow) or possibly execute arbitrary code via crafted text.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | icu | 52.1-9 | — |
| Debian 13 | icu | 52.1-9 | — |
| Debian 12 | icu | 52.1-9 | — |
| Debian 8 | icu | 52.1-8+deb8u2 | DSA-3323-1 |
| Debian 7 | icu | 4.8.1.1-12+deb7u3 | DSA-3323-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 14.04 LTS | icu | 52.1-3ubuntu0.3 | USN-2605-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP3 | icu | 52.1-8.3.1 | SUSE-SU-2018:1401-1, SUSE-SU-2017:2318-1 |
| SLES 12 SP2 | icu | 52.1-8.3.1 | SUSE-SU-2018:1401-2, SUSE-SU-2018:1401-1, SUSE-SU-2017:2318-1 |
| SLES 12 SP1 | icu | 52.1-8.7.1 | SUSE-SU-2018:1401-1 |
| SLES 12 | apache-commons-logging | 1.1.3-7.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | cmis-client | 0.5.0-5.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | flute | 1.3.0-4.2 | SUSE-SU-2015:1915-1 |
| SLES 12 | graphite2 | 1.3.1-3.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | hyphen | 2.8.8-9.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | icu | 52.1-8.7.1 | SUSE-SU-2018:1401-1 |
| SLES 12 | libabw +1 | 0.1.1-5.3 | SUSE-SU-2015:1915-1 |
| SLES 12 | libbase +3 | 1.1.3-4.3 | SUSE-SU-2015:1915-1 |
| SLES 12 | libe-book | 0.1.2-4.2 | SUSE-SU-2015:1915-1 |
| SLES 12 | libetonyek | 0.1.3-3.5 | SUSE-SU-2015:1915-1 |
| SLES 12 | libfonts | 1.1.3-4.9 | SUSE-SU-2015:1915-1 |
| SLES 12 | libfreehand | 0.1.1-4.9 | SUSE-SU-2015:1915-1 |
| SLES 12 | libgltf | 0.0.1-2.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | libixion | 0.9.1-3.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | liblangtag | 0.5.7-3.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | liblayout | 0.2.10-4.8 | SUSE-SU-2015:1915-1 |
| SLES 12 | libloader | 1.1.3-3.2 | SUSE-SU-2015:1915-1 |
| SLES 12 | libmspub | 0.1.2-5.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | libmwaw | 0.3.6-3.3 | SUSE-SU-2015:1915-1 |
| SLES 12 | libodfgen | 0.1.4-3.9 | SUSE-SU-2015:1915-1 |
| SLES 12 | liborcus | 0.7.1-3.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | libpagemaker | 0.0.2-2.3 | SUSE-SU-2015:1915-1 |
| SLES 12 | libreoffice | 5.0.2.2-13.14 | SUSE-SU-2015:1915-1 |
| SLES 12 | libreoffice-share-linker | 1-2.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | libreoffice-voikko | 4.1-6.3 | SUSE-SU-2015:1915-1 |
| SLES 12 | librevenge | 0.0.2-4.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | libserializer | 1.1.2-4.3 | SUSE-SU-2015:1915-1 |
| SLES 12 | libvisio | 0.1.3-4.3 | SUSE-SU-2015:1915-1 |
| SLES 12 | libvoikko | 3.7.1-3.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | libwps | 0.4.1-3.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | malaga-suomi | 1.18-3.2 | SUSE-SU-2015:1915-1 |
| SLES 12 | myspell-dictionaries | 20150827-5.1 | SUSE-SU-2015:1915-1 |
| SLES 12 | pentaho-reporting-flow-engine | 0.9.4-4.5 | SUSE-SU-2015:1915-1 |
| SLES 12 | sac | 1.3-4.1 | SUSE-SU-2015:1915-1 |
| SLES 11 SP4 | google-carlito-fonts | 1.1.03.beta1-2.1 | SUSE-SU-2016:0324-1 |
| SLES 11 SP4 | hyphen | 2.8.8-2.1 | SUSE-SU-2016:0324-1 |
| SLES 11 SP4 | libreoffice | 5.0.4.2-23.1 | SUSE-SU-2016:0324-1 |
| SLES 11 SP4 | libreoffice-share-linker | 1-2.1 | SUSE-SU-2016:0324-1 |
| SLES 11 SP4 | libreoffice-voikko | 4.1-2.26 | SUSE-SU-2016:0324-1 |
| SLES 11 SP4 | libvoikko | 3.7.1-5.2 | SUSE-SU-2016:0324-1 |
| SLES 11 SP4 | myspell-dictionaries | 20150827-23.1 | SUSE-SU-2016:0324-1 |
| SLES 11 SP4 | mythes | 1.2.4-2.1 | SUSE-SU-2016:0324-1 |
| SLES 11 SP4 | python-importlib | 1.0.2-0.8.1 | SUSE-SU-2016:0324-1 |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP3 | icu | 52.1-8.3.1 | SUSE-SU-2018:1401-1, SUSE-SU-2017:2318-1 |
| SLES for SAP 12 SP2 | icu | 52.1-8.3.1 | SUSE-SU-2018:1401-1, SUSE-SU-2017:2318-1 |
| SLES for SAP 12 SP1 | icu | 52.1-8.7.1 | SUSE-SU-2018:1401-1 |
| SLES for SAP 12 | apache-commons-logging | 1.1.3-7.1 | SUSE-SU-2015:1915-1 |
| SLES for SAP 12 | graphite2 | 1.3.1-3.1 | SUSE-SU-2015:1915-1 |
| SUSE OpenStack Cloud 7 | icu | 52.1-8.7.1 | SUSE-SU-2018:1401-1 |
| SUSE Enterprise Storage 4 | icu | 52.1-8.7.1 | SUSE-SU-2018:1401-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | libreoffice | 5.2.3.3-2.2 | openSUSE-SU-2024:10006-1 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
Exploit-DB 1
- ICU library 52 < 54 - Multiple Vulnerabilities EDB-43887 · local · Jun 10, 2015
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 10
- USN-2605-1 icu vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DSA-3323-1 icu - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2016:0324-1 Recommended update for LibreOffice SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2018:1401-1 Security update for icu SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:2318-1 Security update for icu SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2015:1915-1 Recommended update for LibreOffice SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2018:1401-2 Security update for icu SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10006-1 libreoffice-5.2.3.3-2.2 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2025-1660 Oracle Utilities: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jul 28, 2025
- WID-SEC-2024-3232 International Components for Unicode (ICU): Schwachstelle ermöglichen Ausführen von beliebigem Programmcode mit Benutzerrechten BSI CERT-Bund (WID) · Oct 17, 2024
References
- https://support.apple.com/HT205221
- https://raw.githubusercontent.com/pedrib/PoC/master/generic/i-c-u-fail.txt
- http://bugs.icu-project.org/trac/changeset/37162
- https://support.apple.com/HT205212
- APPLE-SA-2015-09-30-3 vendor-advisory
- http://www.oracle.com/technetwork/topics/security/cpuoct2015-2367953.html
- GLSA-201507-04 vendor-advisory
- VU#602540 third-party-advisory
- https://support.apple.com/HT205267
- 20150505 [CVE-2014-8146/8147] - ICU heap and integer overflows / I-C-U-FAIL mailing-list
- APPLE-SA-2015-09-21-1 vendor-advisory
- APPLE-SA-2015-09-16-3 vendor-advisory
- [oss-security] 20150505 [CVE-2014-8146/8147] - ICU heap and integer overflows / I-C-U-FAIL mailing-list
- https://support.apple.com/HT205213
- 74457 vdb-entry
- APPLE-SA-2015-09-16-1 vendor-advisory
- DSA-3323 vendor-advisory
- http://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html
- https://www.oracle.com/technetwork/security-advisory/cpuapr2019-5072813.html