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Cyrus-sasl: heap buffer overflow in cyrus-sasl add_to_challenge() allows malicious server to crash or compromise digest-md5 clients

Type: advisorySource: Official CVE List1 source record

A heap-based buffer overflow flaw was found in Cyrus SASL. The add_to_challenge() function in the DIGEST-MD5 plugin computes the size of the buffer needed for a challenge/response field before DIGEST-MD5 quoting is applied, but does not recompute that size when quoting (escaping special characters) makes the value longer. The under-sized buffer is then passed to strcat(), causing a heap-based out-of-bounds write whose size depends on attacker-controlled input. A malicious or on-path DIGEST-MD5 (or HTTP Digest) server can trigger this flaw in a connecting client by supplying a crafted challenge field, such as realm or nonce, most likely resulting in a crash of the client application.

Announced Group revision 1
Original source ↗

CVE-2026-107161

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-107161

Red Hat Enterprise Linux 10

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Red Hat Enterprise Linux 6

Source reference: /containers/cna/affected/1/product

Affected versions
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Fixed versions
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Prerequisites
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Red Hat Enterprise Linux 7

Source reference: /containers/cna/affected/2/product

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Fixed versions
Not stated in this record
Prerequisites
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Red Hat Enterprise Linux 8

Source reference: /containers/cna/affected/3/product

Affected versions
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Fixed versions
Not stated in this record
Prerequisites
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Red Hat Enterprise Linux 9

Source reference: /containers/cna/affected/4/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Red Hat Hardened Images

Source reference: /containers/cna/affected/5/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Red Hat OpenShift Container Platform 4

Source reference: /containers/cna/affected/6/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Red Hat OpenShift Container Platform 4

Source reference: /containers/cna/affected/7/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:10"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 10",
    "packageName": "cyrus-sasl",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:6"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 6",
    "packageName": "cyrus-sasl",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "unknown"
  },
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:7"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 7",
    "packageName": "cyrus-sasl",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:8"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 8",
    "packageName": "cyrus-sasl",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:9"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 9",
    "packageName": "cyrus-sasl",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/a:redhat:hummingbird:1"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Hardened Images",
    "packageName": "cyrus-sasl",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/a:redhat:openshift:4"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat OpenShift Container Platform 4",
    "packageName": "openshift/ose-rhel-coreos-8",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "unaffected"
  },
  {
    "cpes": [
      "cpe:/a:redhat:openshift:4"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat OpenShift Container Platform 4",
    "packageName": "openshift/ose-rhel-coreos-9",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "unaffected"
  }
]
Related CVEs
CVE-2026-107161

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#16547 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement

Revision history

  1. CVE-2026-107161 · Revision 1Source updated