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CVE-2026-61908

An issue was discovered in Cyrus IMAP before 3.12.4. A JMAP email-header blob ID can reference an...

3.1 LowFix available

An issue was discovered in Cyrus IMAP before 3.12.4. A JMAP email-header blob ID can reference an out-of-bounds index. An authenticated user could attempt to download a crafted JMAP blob ID of the form H<emailid>-<index>, which could read past the end of the internal blob_headers array during download, exposing adjacent heap memory.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
None
Availability
None

Exploit likelihood

0.22%Unchanged since Sep 10, 2026
90%50%10%1%

What each source reports

CVE List Score used 3.1

An issue was discovered in Cyrus IMAP before 3.12.4. A JMAP email-header blob ID can reference an out-of-bounds index. An authenticated user could attempt to download a crafted JMAP blob ID of the form H<emailid>-<index>, which could read past the end of the internal blob_headers array during download, exposing adjacent heap memory.

Record
CVE-2026-61908
CVSS 3.1
3.1 LowCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-125
Updated
2026-11-02
EUVDEUVD-2026-75134 3.1

An issue was discovered in Cyrus IMAP before 3.12.4. A JMAP email-header blob ID can reference an out-of-bounds index. An authenticated user could attempt to download a crafted JMAP blob ID of the form H<emailid>-<index>, which could read past the end of the internal blob_headers array during download, exposing adjacent heap memory.

Record
EUVD-2026-75134
CVSS 3.1
3.1 LowCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-2x93-wv63-897r 3.1

An issue was discovered in Cyrus IMAP before 3.12.4. A JMAP email-header blob ID can reference an...

An issue was discovered in Cyrus IMAP before 3.12.4. A JMAP email-header blob ID can reference an out-of-bounds index. An authenticated user could attempt to download a crafted JMAP blob ID of the form H<emailid>-<index>, which could read past the end of the internal blob_headers array during download, exposing adjacent heap memory.

Record
GHSA-2x93-wv63-897r
CVSS 3.1
3.1 LowCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-125
Updated
2026-11-02
NVD 3.1

An issue was discovered in Cyrus IMAP before 3.12.4. A JMAP email-header blob ID can reference an out-of-bounds index. An authenticated user could attempt to download a crafted JMAP blob ID of the form H<emailid>-<index>, which could read past the end of the internal blob_headers array during download, exposing adjacent heap memory.

Record
CVE-2026-61908
CVSS 3.1
3.1 LowCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-125
Updated
2026-11-02
OSV 3.1

An issue was discovered in Cyrus IMAP before 3.12.4. A JMAP email-header blob ID can reference an out-of-bounds index. An authenticated user could attempt to download a crafted JMAP blob ID of the form H<emailid>-<index>, which could read past the end of the internal blob_headers array during download, exposing adjacent heap memory.

Record
CVE-2026-61908
CVSS 3.1
3.1 LowCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-125
Updated
2026-11-02
OSVDEBIAN-CVE-2026-61908 6.5

An issue was discovered in Cyrus IMAP before 3.12.4. A JMAP email-header blob ID can reference an out-of-bounds index. An authenticated user could attempt to download a crafted JMAP blob ID of the form H<emailid>-<index>, which could read past the end of the internal blob_headers array during download, exposing adjacent heap memory.

Record
DEBIAN-CVE-2026-61908
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVUBUNTU-CVE-2026-61908 3.1

An issue was discovered in Cyrus IMAP before 3.12.4. A JMAP email-header blob ID can reference an out-of-bounds index. An authenticated user could attempt to download a crafted JMAP blob ID of the form H<emailid>-<index>, which could read past the end of the internal blob_headers array during download, exposing adjacent heap memory.

Record
UBUNTU-CVE-2026-61908
CVSS 3.1
3.1 LowCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVopenSUSE-SU-2026:21929-1 No score

Security update for cyrus-imapd

This update for cyrus-imapd fixes the following issues:

Changes in cyrus-imapd:

Update to 3.8.8 (bugfix release):

  • CVE-2026-61907: JMAP snooze bypasses destination-mailbox ACL (bsc#1279908)
  • CVE-2026-61908: JMAP email-header blob ID out-of-bounds index (bsc#1279975)
  • CVE-2026-61909: CalDAV/CardDAV multiget bypasses per-href ACL (bsc#1279976)
  • CVE-2026-61910: Mailbox/set let sharee change special-use role on shared mailboxes (bsc#1279977)
  • CVE-2026-61911: Sieve mailbox existence oracle (bsc#1279978)
  • CVE-2026-61915: VPATCH BYPARAM double-free (bsc#1279979)
Record
openSUSE-SU-2026:21929-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
cyrus-imapd
Debian:12
 All versions, plus listed versions
3.10.0-13.10.0~beta1-13.10.0~beta1-23.10.0~beta1-33.10.0~beta2-1
Show 40 moreShow less
3.10.0~rc2-13.10.1-13.10.1-23.10.1-33.10.1-3~bpo12+13.10.2-13.10.2-1~bpo12+13.12.0-13.12.0-23.12.1-13.12.1-23.12.1-33.12.2-13.12.3-13.12.3-1~bpo13+13.12.3-23.12.3-33.12.3-43.12.4-13.6.1-43.6.1-4+deb12u13.6.1-4+deb12u23.6.1-4+deb12u33.6.1-4+deb12u43.6.1-4+deb12u53.8.0-13.8.0-23.8.0-33.8.0-43.8.0-53.8.0~beta1-13.8.0~beta2-13.8.0~rc1-13.8.1-13.8.1-1~bpo12+13.8.1-23.8.1-33.8.2-13.8.3-13.8.4-1
 None known
cyrus-imapd
Debian:13
 All versions, plus listed versions
3.10.2-13.10.2-1+deb13u13.10.2-1+deb13u23.12.0-13.12.0-2
Show 10 moreShow less
3.12.1-13.12.1-23.12.1-33.12.2-13.12.3-13.12.3-1~bpo13+13.12.3-23.12.3-33.12.3-43.12.4-1
 None known
cyrus-imapd
Debian:14
 before 3.12.4-1, plus listed versions
3.10.2-13.12.0-13.12.0-23.12.1-13.12.1-2
Show 7 moreShow less
3.12.1-33.12.2-13.12.3-13.12.3-1~bpo13+13.12.3-23.12.3-33.12.3-4
3.12.4-1
cyrus-imapd
Ubuntu:Pro:18.04:LTS
 All versions, plus listed versions
2.5.10-3build12.5.10-3build22.5.10-3ubuntu12.5.10-3ubuntu1.12.5.10-3ubuntu1.1+esm1
 None known
cyrus-imapd
Ubuntu:Pro:20.04:LTS
 All versions, plus listed versions
3.0.11-13.0.11-1build13.0.12-13.0.12-23.0.12-2ubuntu2
Show 7 moreShow less
3.0.12-2ubuntu33.0.13-2ubuntu13.0.13-3ubuntu13.0.13-4ubuntu13.0.13-53.0.13-5ubuntu0.1~esm13.0.13-5ubuntu0.1~esm2
 None known
cyrus-imapd
Ubuntu:Pro:22.04:LTS
 All versions, plus listed versions
3.2.6-2build13.4.2-23.4.2-2build13.4.3-23.4.3-3
Show 5 moreShow less
3.4.3-3build23.4.3-3ubuntu0.13.4.3-3ubuntu0.1+esm13.4.3-3ubuntu0.33.4.3-3ubuntu0.3+esm1
 None known
cyrus-imapd
Ubuntu:Pro:24.04:LTS
 All versions, plus listed versions
3.8.0-53.8.1-13.8.1-1build13.8.1-1build23.8.1-3
Show 5 moreShow less
3.8.1-3build33.8.2-13.8.2-1ubuntu0.1~esm13.8.2-1ubuntu0.23.8.2-1ubuntu0.2+esm1
 None known
cyrus-imapd
Ubuntu:26.10
 All versions, plus listed versions
3.12.1-33.12.2-13.12.2-1build13.12.3-3build1
 None known
cyrus-imapd
Ubuntu:26.04:LTS
 All versions, plus listed versions
3.10.2-13.12.1-23.12.1-2build13.12.1-3
 None known
cyrus-imapd
openSUSE:Leap 16.0
From an advisory covering 6 CVEs
 before 3.8.8-bp160.1.1
3.8.8-bp160.1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-61908 is a low vulnerability (CVSS 3.1) in Cyrus Imap, published September 9, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.22%, the 13th percentile. Fixed in cyrus-imapd 3.12.4-1.

References

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