libicu in International Components for Unicode (ICU) 3.8.1 and earlier attempts to process backreferences to the nonexistent capture group z
Noroxi assessment
Priority: Monitor (action score 28/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 2.9% (FIRST EPSS); higher than 86.7% of all records.
- Fixed version: icu (Debian:12) 3.8-6; icu (Debian:4.0) 3.6-2etch1; icu (openSUSE:Tumbleweed) 69.1-2.3.
Low priority for now. Upgrade to icu (Debian:12) 3.8-6; icu (Debian:4.0) 3.6-2etch1; icu (openSUSE:Tumbleweed) 69.1-2.3 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
libicu in International Components for Unicode (ICU) 3.8.1 and earlier attempts to process backreferences to the nonexistent capture group zero (aka \0), which might allow context-dependent attackers to read from, or write to, out-of-bounds memory locations, related to corruption of REStackFrames.
- Published
- Jan 28, 2008
- Updated
- Jun 16, 2026
- EPSS
- 2.9% · 87th percentile
- CWE
- CWE-399
Report tools
Action score
28
Monitor
Low priority for now.
- CVSS
- 27 / 40 · 6.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 2.9%
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Is your version affected? Check itNoroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| icu-project | international components for unicode | cpe:2.3:a:icu-project:international_components_for_unicode |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- icu-project international components for unicodeup to 3.8.1 inclusive
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | icu | before 3.8-6 | 3.8-6 |
| Debian:4.0 | icu | before 3.6-2etch1 | 3.6-2etch1 |
| openSUSE:Tumbleweed | icu | before 69.1-2.3 | 69.1-2.3 |
| Red Hat:enterprise_linux:5::client | libicu | before 0:3.6-5.11.1 | 0:3.6-5.11.1 |
| Red Hat:enterprise_linux:5::client | libicu-doc | before 0:3.6-5.11.1 | 0:3.6-5.11.1 |
| Red Hat:enterprise_linux:5::client_workstation | icu | before 0:3.6-5.11.1 | 0:3.6-5.11.1 |
| Red Hat:enterprise_linux:5::client_workstation | icu-debuginfo | before 0:3.6-5.11.1 | 0:3.6-5.11.1 |
| Red Hat:enterprise_linux:5::client_workstation | libicu-devel | before 0:3.6-5.11.1 | 0:3.6-5.11.1 |
Same product
icu-project: all recordsOther highest-scoring records for the same primary product.
- CVE-2017-14952Double free in i18n/zonemeta.cpp in International Components for Unicode (ICU) for C/C++ through 59.1 allows remote attackers to execute arb41Plan
- CVE-2014-9911Stack-based buffer overflow in the ures_getByKeyWithFallback function in common/uresbund.cpp in International Components for Unicode (ICU) b41Plan
- CVE-2016-7415Stack-based buffer overflow in the Locale class in common/locid.cpp in International Components for Unicode (ICU) through 57.1 for C/C++ all41Plan
- CVE-2016-6293The uloc_acceptLanguageFromHTTP function in common/uloc.cpp in International Components for Unicode (ICU) through 57.1 for C/C++ does not en41Plan
- CVE-2018-18928International Components for Unicode (ICU) for C/C++ 63.1 has an integer overflow in number::impl::DecimalQuantity::toScientificString() in 40Plan
- CVE-2017-17484The ucnv_UTF8FromUTF8 function in ucnv_u8.cpp in International Components for Unicode (ICU) for C/C++ through 60.1 mishandles ucnv_convertEx40Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:icu | 3.8-6 · Debian:12 | Package registry (OSV) |
| opensuse:icu | 69.1-2.3 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:icu | 0:3.6-5.11.1 · Red Hat:enterprise_linux:5::client_workstation | Package registry (OSV) |
| red hat:icu-debuginfo | 0:3.6-5.11.1 · Red Hat:enterprise_linux:5::client_workstation | Package registry (OSV) |
| red hat:libicu | 0:3.6-5.11.1 · Red Hat:enterprise_linux:5::client | Package registry (OSV) |
| red hat:libicu-devel | 0:3.6-5.11.1 · Red Hat:enterprise_linux:5::client_workstation | Package registry (OSV) |
| red hat:libicu-doc | 0:3.6-5.11.1 · Red Hat:enterprise_linux:5::client | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
If successful
- Confidentiality
- P · data can be read
- Integrity
- P · data or configuration can be modified
- Availability
- P · the service can be disrupted
- Attack complexity
- M
- Confidentiality impact
- P
- Integrity impact
- P
- Availability impact
- P
Weakness class (CWE)
CWE-399 · Resource Management ErrorsCVSS vector
AV:N/AC:M/Au:N/C:P/I:P/A:P
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- lists.opensuse.org/opensuse-security-announce/2008-03/msg00001.html
- rhn.redhat.com/errata/RHSA-2008-0090.html
- secunia.com/advisories/28575
- secunia.com/advisories/28615
- secunia.com/advisories/28669
- secunia.com/advisories/28783
- secunia.com/advisories/29194
- secunia.com/advisories/29242
- secunia.com/advisories/29291
- secunia.com/advisories/29294
- secunia.com/advisories/29333
- secunia.com/advisories/29852
- secunia.com/advisories/29910
- secunia.com/advisories/29987
- secunia.com/advisories/30179
- security.gentoo.org/glsa/glsa-200803-20.xml
- security.gentoo.org/glsa/glsa-200805-16.xml
- securitytracker.com/id?1019269
- sourceforge.net/mailarchive/message.php?msg_name=d03a2ffb0801221538x68825e42xb4a4aaf0fcccecbd%40mail.gmail.com
- sunsolve.sun.com/search/document.do?assetkey=1-26-231641-1
Vendor advisories and official records. Exploit/PoC links are deliberately left out.