Evidence used
- No CISA KEV confirmation is currently recorded.
- A structured source references public exploit or proof-of-concept material.
- EPSS is 0.13% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-90996High confidence
Sssd: sssd: denial of service in nss responder via crafted zero-length requests
Red Hat · Red Hat Enterprise Linux 10
4.0MediumCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productMedium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 169 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityMedium→Operational priority:Medium, unchanged from published severity.unchanged
Compensating controls
- Apply the linked authoritative mitigation while planning the permanent fix.
- Restrict local access and enforce least privilege on affected hosts.
- Increase monitoring for the attack path and post-exploitation behaviour described in the report.
Verification
- Confirm that the asset runs Red Hat Red Hat Enterprise Linux 10 and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 169 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 166 affected or under-investigation product states without a fixed product state in the same current advisory
- Debian Security Tracker: 3 affected package states with no published fix
Distribution package intelligence
4 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Package result overrides the generic status
BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 3 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | sssd | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 9 Oct 2026 |
| Debian bookwormbookworm · source | sssd | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 9 Oct 2026 |
| Debian sidsid · source | sssd | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 9 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | sssd | Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 8 Oct 2026 |
Direct vendor intelligence
1 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
CVE-2026-90996 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitysssd: sssd: Denial of Service in NSS responder via crafted zero-length requests
The vendor explicitly identifies these products as affected by this CVE.
- libipa_hbac as a component of Red Hat Enterprise Linux 10
- libsss_autofs as a component of Red Hat Enterprise Linux 10
- libsss_certmap as a component of Red Hat Enterprise Linux 10
- libsss_idmap as a component of Red Hat Enterprise Linux 10
- libsss_nss_idmap as a component of Red Hat Enterprise Linux 10
- libsss_nss_idmap-devel as a component of Red Hat Enterprise Linux 10
- libsss_sudo as a component of Red Hat Enterprise Linux 10
- python3-libipa_hbac as a component of Red Hat Enterprise Linux 10
- python3-libsss_nss_idmap as a component of Red Hat Enterprise Linux 10
- python3-sss as a component of Red Hat Enterprise Linux 10
- python3-sss-murmur as a component of Red Hat Enterprise Linux 10
- python3-sssdconfig as a component of Red Hat Enterprise Linux 10
- Summary
- A flaw was found in sssd. A local unprivileged user could send a specially crafted request with a zero-length body to the Network Security Services (NSS) responder. This could lead to a denial-of-service condition, causing the NSS responder to become unstable or terminate. This vulnerability affects the availability of the system responder.
- Remediation
- There's no appropriated mitigation for this issue.
Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 169 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
A flaw was found in sssd. A local unprivileged user could send a specially crafted request with a zero-length body to the Network Security Services (NSS) responder. This could lead to a denial-of-service condition, causing the NSS responder to become unstable or terminate. This vulnerability affects the availability of the system responder.
What
A flaw was found in sssd. A local unprivileged user could send a specially crafted request with a zero-length body to the Network Security Services (NSS) responder. This could lead to a denial-of-service condition, causing the NSS responder to become unstable or terminate. This vulnerability affects the availability of the system responder.
Why
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
How
An attacker operating through local access may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
A flaw was found in sssd. A local unprivileged user could send a specially crafted request with a zero-length body to the Network Security Services (NSS) responder. This could lead to a denial-of-service condition, causing the NSS responder to become unstable or terminate. This vulnerability affects the availability of the system responder.
Why
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
How
An attacker operating through local access may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material Reference recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.
- Likely attack path
- local access → Integer Underflow (Wrap or Wraparound) → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Local
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-191 ↗
CWE-191: Integer Underflow (Wrap or Wraparound). The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:LCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.ALowAvailability impact: A successful attack can cause a limited loss.- Post-exploitation / living off the land
- The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix availability varies by product
- Affected
- libipa_hbac as a component of Red Hat Enterprise Linux 10
- libsss_autofs as a component of Red Hat Enterprise Linux 10
- libsss_certmap as a component of Red Hat Enterprise Linux 10
- libsss_idmap as a component of Red Hat Enterprise Linux 10
- libsss_nss_idmap as a component of Red Hat Enterprise Linux 10
- libsss_nss_idmap-devel as a component of Red Hat Enterprise Linux 10
- libsss_sudo as a component of Red Hat Enterprise Linux 10
- python3-libipa_hbac as a component of Red Hat Enterprise Linux 10
- python3-libsss_nss_idmap as a component of Red Hat Enterprise Linux 10
- python3-sss as a component of Red Hat Enterprise Linux 10
- python3-sss-murmur as a component of Red Hat Enterprise Linux 10
- python3-sssdconfig as a component of Red Hat Enterprise Linux 10
- sssd as a component of Red Hat Enterprise Linux 10
- sssd-ad as a component of Red Hat Enterprise Linux 10
- sssd-client as a component of Red Hat Enterprise Linux 10
- sssd-common as a component of Red Hat Enterprise Linux 10
- sssd-common-pac as a component of Red Hat Enterprise Linux 10
- sssd-dbus as a component of Red Hat Enterprise Linux 10
- sssd-idp as a component of Red Hat Enterprise Linux 10
- sssd-ipa as a component of Red Hat Enterprise Linux 10
- sssd-kcm as a component of Red Hat Enterprise Linux 10
- sssd-krb5 as a component of Red Hat Enterprise Linux 10
- sssd-krb5-common as a component of Red Hat Enterprise Linux 10
- sssd-ldap as a component of Red Hat Enterprise Linux 10
- sssd-nfs-idmap as a component of Red Hat Enterprise Linux 10
- sssd-passkey as a component of Red Hat Enterprise Linux 10
- sssd-proxy as a component of Red Hat Enterprise Linux 10
- sssd-tools as a component of Red Hat Enterprise Linux 10
- sssd-winbind-idmap as a component of Red Hat Enterprise Linux 10
- sssd.src as a component of Red Hat Enterprise Linux 10
- and 136 more
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- Workaround
- There's no appropriated mitigation for this issue.
04
Evidence and provenance
Published 14 Sept 2026 · Last source change 7 Oct 2026, 15:25 UTC · CWE-191 · Integer Underflow (Wrap or Wraparound)
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-09-15
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-77590
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD enriched
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Vendor guidanceAuthoritative vendor guidance changed: added mitigation: bugzilla.redhat.com/show_bug.cgi?id=2478986; added remediation: bugzilla.redhat.com/show_bug.cgi?id=2478986; 1 further additions.secalert@redhat.com ↗
- Before
- no authoritative guidance recorded
- After
- mitigation: bugzilla.redhat.com/show_bug.cgi?id=2478986 · remediation: bugzilla.redhat.com/show_bug.cgi?id=2478986 · vendor advisory: access.redhat.com/CVE-2026-90996
- Remediation statusRemediation status changed from Awaiting fix to Mitigation available.secalert@redhat.com ↗
- Before
- Awaiting fix
- After
- Mitigation available
- Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.secalert@redhat.com ↗
- Before
- No public exploit
- After
- Public exploit reference
- Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-90996 to remediation: access.redhat.com/CVE-2026-90996.Red Hat Product Security ↗
- Before
- remediation: access.redhat.com/CVE-2026-90996
- After
- remediation: access.redhat.com/CVE-2026-90996
- ENISA EUVD mappingEUVD-2026-77590 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-77590"}
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
CVE published
Mitigation reference recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.