libexpat before 2.7.5 allows a NULL pointer dereference with empty external parameter entity content.
- Published
- Mar 16, 2026
- Updated
- Jul 14, 2026
- EPSS
- 0.2% · 4th percentile
- CWE
- CWE-476
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Report tools
Action score
22
Monitor
Low priority for now.
- CVSS
- 22 / 40 · 5.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.2%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 5.5
- CNA · mitre
- 4.0
- 1.5 point gap
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| libexpat project | libexpat | cpe:2.3:a:libexpat_project:libexpat |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- libexpat project libexpatbefore 2.7.5
Versions reported by the vendor
Affected version ranges reported by the assigning authority (mitre). Independent of NVD's CPE analysis and usually ahead of it.
libexpat project libexpat
- before 2.7.5affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.20 | expat | before 2.7.5-r0 | 2.7.5-r0 |
| Debian:12 | expat | before 2.5.0-1+deb12u4 | 2.5.0-1+deb12u4 |
| Debian:13 | expat | before 2.8.2-1~deb13u1 | 2.8.2-1~deb13u1 |
| Debian:14 | expat | before 2.7.5-1 | 2.7.5-1 |
| openSUSE:Leap 16.0 | expat | before 2.7.1-160000.5.1 | 2.7.1-160000.5.1 |
| openSUSE:Tumbleweed | expat | before 2.7.5-1.1 | 2.7.5-1.1 |
| openSUSE:Tumbleweed | mozjs115 | before 115.15.0-8.1 | 115.15.0-8.1 |
| openSUSE:Tumbleweed | mozjs140 | before 140.10.0-1.1 | 140.10.0-1.1 |
| SUSE:Linux Enterprise Micro 5.2 | expat | before 2.7.1-150000.3.45.1 | 2.7.1-150000.3.45.1 |
| SUSE:Linux Enterprise Micro 5.3 | expat | before 2.7.1-150400.3.37.1 | 2.7.1-150400.3.37.1 |
| SUSE:Linux Enterprise Micro 5.3 | expat | before 2.7.1-150400.3.37.1 | 2.7.1-150400.3.37.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | expat | before 2.7.1-150700.3.12.1 | 2.7.1-150700.3.12.1 |
| SUSE:Linux Enterprise Server 12 SP5-LTSS | expat | before 2.7.1-21.52.1 | 2.7.1-21.52.1 |
| SUSE:Linux Micro 6.0 | expat | before 2.7.1-5.1 | 2.7.1-5.1 |
| SUSE:Linux Micro 6.1 | expat | before 2.7.1-slfo.1.1_5.1 | 2.7.1-slfo.1.1_5.1 |
| SUSE:Linux Micro 6.2 | expat | before 2.7.1-160000.5.1 | 2.7.1-160000.5.1 |
Same product
libexpat project: all recordsOther highest-scoring records for the same primary product.
- CVE-2022-25236xmlparse.c in Expat (aka libexpat) before 2.4.5 allows attackers to insert namespace-separator characters into namespace URIs.50Plan
- CVE-2022-25315In Expat (aka libexpat) before 2.4.5, there is an integer overflow in storeRawNames.40Plan
- CVE-2022-25235xmltok_impl.c in Expat (aka libexpat) before 2.4.5 lacks certain validation of encoding, such as checks for whether a UTF-8 character is val40Plan
- CVE-2022-23852Expat (aka libexpat) before 2.4.4 has a signed integer overflow in XML_GetBuffer, for configurations with a nonzero XML_CONTEXT_BYTES.40Plan
- CVE-2022-22824defineAttribute in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.40Plan
- CVE-2022-22823build_model in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.40Plan
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 |
|---|---|---|
| libexpat project libexpat | 2.7.5 | Vendor (CNA) |
| azl3 expat 2.6.4-4 on Azure Linux 3.0 | 2.6.4-5 · CBL-Mariner Releases | Microsoft (MSRC) |
| azl3 expat 2.6.4-5 on Azure Linux 3.0 | 2.6.4-5 · CBL-Mariner Releases | Microsoft (MSRC) |
| cbl2 expat 2.6.4-4 on CBL Mariner 2.0 | 2.6.4-5 · CBL-Mariner Releases | Microsoft (MSRC) |
| cbl2 expat 2.6.4-4 on CBL-Mariner 2.0 | 2.6.4-5 · Release Notes | Microsoft (MSRC) |
| alpine:expat | 2.7.5-r0 · Alpine:v3.20 | Package registry (OSV) |
| debian:expat | 2.5.0-1+deb12u4 · Debian:12 | Package registry (OSV) |
| debian:expat | 2.8.2-1~deb13u1 · Debian:13 | Package registry (OSV) |
| opensuse:expat | 2.7.1-150400.3.37.1 · openSUSE:Leap 15.6 | Package registry (OSV) |
| opensuse:mozjs115 | 115.15.0-8.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:mozjs140 | 140.10.0-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| suse:expat | 2.7.1-150000.3.45.1 · SUSE:Linux Enterprise Micro 5.2 | Package registry (OSV) |
| suse:expat | 2.7.1-150400.3.37.1 · SUSE:Linux Enterprise Micro 5.3 | 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.
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.
- CVE-2026-327780 days apartlibexpat before 2.7.5 allows a NULL pointer dereference in the function setContext on retry after an earlier ouf-of-memory condition.22Monitor
- CVE-2026-2451552 days apartIn libexpat before 2.7.4, XML_ExternalEntityParserCreate does not copy unknown encoding handler user data.10Monitor
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
- Someone with local access to the system can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-476 · NULL Pointer DereferenceCVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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
- github.com/libexpat/libexpat/pull/1158
- github.com/libexpat/libexpat/pull/1159
- cert-portal.siemens.com/productcert/html/ssa-082556.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.