Security readout for executives and security teams
Plain-English summary
CVE-2026-1539 is a credential leakage flaw in libsoup. During HTTP redirects to another host, proxy authentication credentials may be forwarded to the redirected server. This can expose proxy credentials to third parties if affected applications use libsoup with authenticated proxies.
Executive priority
Treat this as a moderate confidentiality risk. It is not a system takeover issue, but leaked proxy credentials can enable unauthorized network access or monitoring. Prioritize environments using authenticated proxies with internet-facing or redirect-heavy applications.
Technical view
libsoup removes the Authorization header on cross-host redirects but fails to remove Proxy-Authorization. The CVSS 3.1 score is 5.8, with network attack vector, low complexity, no privileges or user interaction, and low confidentiality impact. Red Hat lists libsoup/libsoup3 on RHEL 6 through 10 as affected.
Likely exposure
Organizations using Red Hat Enterprise Linux 6, 7, 8, 9, or 10 with applications that rely on libsoup or libsoup3 and authenticated HTTP proxies are most relevant. Exposure depends on whether those applications follow redirects across hosts while proxy credentials are present.
Exploitation context
The provided sources do not show active exploitation, and the CVE is not listed as KEV. Abuse would require a redirect scenario where an affected libsoup-based application sends proxy credentials to an unintended host.
Researcher notes
Evidence currently identifies the header-stripping logic flaw and Red Hat affected platforms, but not fixed versions in the provided bundle. Validate against vendor package advisories before declaring remediation complete. Avoid assuming impact for products not shown in the sources.
Mitigation direction
- Check Red Hat and GNOME guidance for fixed package availability.
- Update libsoup or libsoup3 packages when vendor fixes are published.
- Limit use of shared or highly privileged proxy credentials.
- Review proxy authentication scope and rotate credentials if leakage is suspected.
- Avoid untrusted redirect flows in affected applications where practical.
Validation and detection
- Inventory systems running affected RHEL releases with libsoup or libsoup3 installed.
- Identify applications using libsoup with authenticated HTTP proxies.
- Review application behavior involving cross-host HTTP redirects.
- Check vendor advisories for fixed package versions and remediation status.
- Look for unusual proxy credential use after redirect-heavy traffic.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-201: Information exposure and cloud metadata lookup
Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-1539 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N3.91.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.8MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://access.redhat.com/security/cve/CVE-2026-1539CVE reference · vdb-entry, x_refsource_REDHAT
- https://gitlab.gnome.org/GNOME/libsoup/-/issues/489CVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Insertion of Sensitive Information Into Sent Data
Insertion of Sensitive Information Into Sent Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.