7.5

CVE-2026-40356: mit kerberos_5 Integer Underflow (Wrap or Wraparound)

CVSS: 7.5v3.1HighAnalyzed
AliasesRHSA-2026:24683RHSA-2026:24685RHSA-2026:24686
Published 28-04-2026Last modified 28-04-2026
Open JSON

Vulnerability summary

CVE-2026-40356 is a high (CVSS 7.5) Integer Underflow (Wrap or Wraparound) vulnerability in mit kerberos_5. EPSS estimates a 0.78% chance of exploitation in the next 30 days, higher than 55.2% of scored vulnerabilities. 1 public exploit is recorded.

Overall risk
40/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (NVD)
EPSS score
0.78%
0%100%
Low · +0.18 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1reference

Advisory lineage

Upstream 0 · Downstream 12 · Related 7
MGASA-2026-0233OPENSUSE-SU-2026:10729-1OPENSUSE-SU-2026:21021-1RHSA-2026:12220RHSA-2026:16799RHSA-2026:19145

Timeline

  1. 28-04-2026
    PublishedVulnerability first disclosed.
  2. 28-04-2026
    Last modifiedVulnerability information updated.

Description

In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, possibly causing the process to terminate in parse_message.

CVSS metrics

5 scores · 5 sources · 1 version

EPSS trend

Probability

0.78%

Chance of exploitation in the next 30 days

Percentile

55%

Versus all other CVEs

30-day change

+0.18 pp

From 0.60% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.78%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

1 found
  • referenceUnverified

    Exploit Reference (cems.fun)

    Maturity: unknown

Weaknesses

CWE · root cause

Affected systems

Redhat16 products
  • krb5< 0:1.21.1-8.el9_6.2 | < 0:1.20.1-9.el9_2.6 | < 0:1.21.1-2.el9_4.5
  • krb5-debuginfo< 0:1.21.1-8.el9_6.2 | < 0:1.20.1-9.el9_2.6 | < 0:1.21.1-2.el9_4.5
  • krb5-debugsource< 0:1.21.1-8.el9_6.2 | < 0:1.20.1-9.el9_2.6 | < 0:1.21.1-2.el9_4.5
  • krb5-devel< 0:1.21.1-8.el9_6.2 | < 0:1.20.1-9.el9_2.6 | < 0:1.21.1-2.el9_4.5
  • krb5-libs< 0:1.21.1-8.el9_6.2 | < 0:1.20.1-9.el9_2.6 | < 0:1.21.1-2.el9_4.5
Debian1 product
  • krb5< 1.20.1-2+deb12u5 | < 1.21.3-5+deb13u1 | < 1.22.1-2.1
Mit1 product
  • kerberos_5≥ 1.18, < 1.22.3 | ≥ 1.18.0, ≤ 1.22.2
Ubuntu1 product
  • krb5< 1.19.2-2ubuntu0.8 | < 1.20.1-6ubuntu2.7 | All versions (No fix recorded) | < 1.22.1-2ubuntu4.1

4 vendors · 19 products

References

17 links
Show all 17 references