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No exploitation reportedFix available

CVE-2026-107937

Apache CXF: The attachment header size and count limits can be bypassed, which allows denial of service through memory exhaustion.

No exploitation reported by the sources we read.

  • Published2026-10-09
  • Fixed in4.2.4 · 4.1.9 · 3.6.13
  • WeaknessCWE-770

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

In Apache CXF, the parser for multipart/MTOM attachment part headers did not fully enforce the configured attachment-max-header-size (default 300 characters) and attachment-headers-max-count (default 500) limits. The size limit was applied only to each physical line, not to a header value built from continuation lines or to the combined values of a repeated header. The count limit was checked against the number of distinct header names, not the total number of header lines. A remote, unauthenticated attacker could send a multipart request with very large folded or repeated part headers. The server would then allocate memory without bound, causing a denial of service.  Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Timeline

dates in UTC
  1. 2026-10-0911:17CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 15:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-107937?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-107937?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Apache cxf
BranchAffectedFixed in
4.2≥ 4.2.0, < 4.2.44.2.4
4.x≥ 4.0.0, < 4.1.94.1.9
3.6< 3.6.133.6.13

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2026-107937 Red Hat Product Security10 known affected

    org.apache.cxf/cxf-core: Apache CXF: Denial of Service via large multipart attachment headers

    cxf-core as a component of Red Hat build of Apache Camel 4 for Quarkus 3 · cxf-core as a component of Red Hat build of Apache Camel for Spring Boot 4 · cxf-core as a component of Red Hat Fuse 7 · +7 more

Full record on NVD

Fix

  1. Update Apache cxf to 4.2.4 · 4.1.9 · 3.6.13
  2. Workaround from the vendor Red Hat Product Security CVE-2026-107937 · 10 productsMitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
  3. No fix available, says the vendor Red Hat Product Security CVE-2026-107937 · 4 productsAffected
  4. No fix planned, says the vendor Red Hat Product Security CVE-2026-107937 · 5 productsOut of support scope
  5. No fix planned, says the vendor Red Hat Product Security CVE-2026-107937 · 1 productWill not fix

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2026-10-09
Last Modified
2026-10-16
NVD status
Analyzed

Frequently asked questions

What is CVE-2026-107937?

In Apache CXF, the parser for multipart/MTOM attachment part headers did not fully enforce the configured attachment-max-header-size (default 300 characters) and attachment-headers-max-count (default 500) limits. The size limit was applied only to each physical line, not to a header value built from continuation lines or to the combined values of a repeated header. The count limit was checked against the number of distinct header names, not the total number of header lines. A remote, unauthenticated attacker could send a multipart request with very large folded or repeated part headers. The server would then allocate memory without bound, causing a denial of service.  Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Is CVE-2026-107937 actively exploited?

Active exploitation of CVE-2026-107937 has not been confirmed. Its EPSS score was 0.6% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-107937?

CVE-2026-107937 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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