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NVD / CVE Program· CNA Linux

CVE-2026-89541: SUNRPC: harden gss_unwrap_resp_priv length checks

Noroxi assessment

Priority: Monitor (action score 39/100)

  • 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: 0.51% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 3691c4b3488d8ca046b9941e5be30c626dbbbb50, 401f6a5b338d05bb1069ad814d9f77e3c367854f, 81fd7654a8429718adfcb2a7e03496077f547ed0.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 3691c4b3488d8ca046b9941e5be30c626dbbbb50, 401f6a5b338d05bb1069ad814d9f77e3c367854f, 81fd7654a8429718adfcb2a7e03496077f547ed0 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

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: SUNRPC: harden gss_unwrap_resp_priv length checks gss_unwrap_resp_priv() validates the RPCSEC_GSS opaque length with offset = (u8 *)(p) - (u8 *)head->iov_base; if (offset + opaque_len > rcv_buf->len) goto unwrap_failed; maj_stat = gss_unwrap(ctx->gc_gss_ctx, offset, offset + opaque_len, rcv_buf); Both operands are u32 and the sum is computed in u32. A reply with opaque_len near 0xffffffff makes offset + opaque_len wrap to a small value that is below rcv_buf->len, so the bound check passes and gss_unwrap() is called with end < begin. The check also lacks a lower bound, so any opaque_len in [0, GSS_KRB5_TOK_HDR_LEN) is accepted and forwarded to gss_krb5_unwrap_v2(), whose pre-decrypt header reads at ptr+4 and ptr+6 then run past the token. A krb5p NFS server returning a crafted RPCSEC_GSS reply can drive the client into out-of-bounds reads in gss_krb5_unwrap_v2() and the rotate_left() loop that follows. Fix by replacing the single combined check with three guards that are safe in u32 arithmetic and that enforce the RFC 4121 minimum outer token length: if (offset > rcv_buf->len) goto unwrap_failed; if (opaque_len > rcv_buf->len - offset) goto unwrap_failed; if (opaque_len < GSS_KRB5_TOK_HDR_LEN) goto unwrap_failed; The first guard makes the subtraction in the second guard unconditionally safe; offset is derived from a successful xdr_inline_decode() in the head kvec, so in practice it already satisfies the bound. The floor mirrors the server-side check added in commit 5b757c2e57a5 ("SUNRPC: svcauth_gss: enforce krb5 token minimum length").

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Sep 11, 2026
Updated
Oct 19, 2026
EPSS
0.5% · 43th percentile
CWE
—

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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

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When you'll hear from us

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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Noroxi 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.

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Affected 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.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.15affected
    • 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf and later · before 3691c4b3488d8ca046b9941e5be30c626dbbbb50affected · git
    • 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf and later · before 85fa6b12e8f439739ac36ef2aad925f37c8b976aaffected · git
    • 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf and later · before 401f6a5b338d05bb1069ad814d9f77e3c367854faffected · git
    • 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf and later · before 81fd7654a8429718adfcb2a7e03496077f547ed0affected · git
    • 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf and later · before 89a15a50f84d32d4b99db86f957427fcbe20a99aaffected · git
    • 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf and later · before ebcbd2523a8524c3d24e111cdbed8e271d910269affected · git
    • 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf and later · before d395c30d570ca6168f0297b191709927d1258273affected · git
    • 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf and later · before 87831b92112c81db251d46756d65daa4f91af6a2affected · git
    • before 2.6.15not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-89539Sep 11, 2026 · SUNRPC: reject duplicate CREDS_VALUE options
    0Monitor
  • ← EarlierCVE-2026-89540Sep 11, 2026 · sunrpc: init gssp_lock before publishing proc entry
    31Monitor
  • Later →CVE-2026-89542Sep 11, 2026 · SUNRPC: harden gss_krb5_unwrap_v2 against short tokens
    39Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux3691c4b3488d8ca046b9941e5be30c626dbbbb50Vendor (CNA)
Linux Linux401f6a5b338d05bb1069ad814d9f77e3c367854fVendor (CNA)
Linux Linux81fd7654a8429718adfcb2a7e03496077f547ed0Vendor (CNA)
Linux Linux85fa6b12e8f439739ac36ef2aad925f37c8b976aVendor (CNA)
Linux Linux87831b92112c81db251d46756d65daa4f91af6a2Vendor (CNA)
Linux Linux89a15a50f84d32d4b99db86f957427fcbe20a99aVendor (CNA)
Linux Linuxd395c30d570ca6168f0297b191709927d1258273Vendor (CNA)
Linux Linuxebcbd2523a8524c3d24e111cdbed8e271d910269Vendor (CNA)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · Debian:12Package 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.

EPSS, last 120 days

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 researchers

Finders, 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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

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

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records