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CRITICAL

CVE-2026-89537

CVSS v3

9.1

CRITICAL

EPSS Score

0.5 %

exploit probability, as of 2026-09-28

CISA KEV

No

known exploited

Exploitation

—

SSVC status

Description

In the Linux kernel, the following vulnerability has been resolved: SUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2 gss_krb5_verify_mic_v2() reads the token ID at ptr[0..1], the flags byte at ptr[2], and padding at ptr[3..7], then passes ptr + GSS_KRB5_TOK_HDR_LEN and cksum_len to gss_krb5_mic_build_sg(). None of these accesses check read_token->len first. The minimum safe token size is GSS_KRB5_TOK_HDR_LEN (16) plus ctx->krb5e->cksum_len (12-24, depending on the enctype).

Technical details

Published
2026-09-11
Last Modified
2026-09-13

Frequently asked questions

What is CVE-2026-89537?

In the Linux kernel, the following vulnerability has been resolved: SUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2 gss_krb5_verify_mic_v2() reads the token ID at ptr[0..1], the flags byte at ptr[2], and padding at ptr[3..7], then passes ptr + GSS_KRB5_TOK_HDR_LEN and cksum_len to gss_krb5_mic_build_sg(). None of these accesses check read_token->len first. The minimum safe token size is GSS_KRB5_TOK_HDR_LEN (16) plus ctx->krb5e->cksum_len (12-24, depending on the enctype).

Is CVE-2026-89537 actively exploited?

Active exploitation of CVE-2026-89537 has not been confirmed. Its EPSS score was 0.5% on 2026-09-28, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-89537?

CVE-2026-89537 has a CVSS v3 base score of 9.1 (CRITICAL severity).

Is CVE-2026-89537 affecting your environment?

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