CVE-2026-110249: Denial-of-service in the Exchange email component
Noroxi assessment
Priority: Monitor (action score 34/100)
- 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: 0.18% (FIRST EPSS).
- Someone with local access to the system can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
- Fixed version: thunderbird (Debian:12) 1:153.5.1esr-1~deb12u1; thunderbird (Debian:13) 1:153.5.1esr-1~deb13u1; thunderbird (Debian:14) 1:153.5.0esr-1.
Low priority for now. Upgrade to thunderbird (Debian:12) 1:153.5.1esr-1~deb12u1; thunderbird (Debian:13) 1:153.5.1esr-1~deb13u1; thunderbird (Debian:14) 1:153.5.0esr-1 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
A malicious, compromised, or MITM-controlled Exchange server can return a single well-formed SOAP response containing an element with enough attributes to keep Thunderbird's main thread CPU-bound for seconds to hours. This vulnerability was fixed in Thunderbird 158 and Thunderbird 153.5.
- Published
- Oct 13, 2026
- Updated
- Oct 21, 2026
- EPSS
- 0.1% · 7th percentile
- CWE
- CWE-400
Report tools
Action score
34
Monitor
Low priority for now.
- CVSS
- 34 / 40 · 8.6 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.1%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
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
If any of these changes, we'll tell you in the daily email digest.
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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.
We use this product, ask for helpAffected 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 (mozilla). Independent of NVD's CPE analysis and usually ahead of it.
Mozilla Thunderbird
- 153.5 and later · up to and including 153.*not affected · rpm
- 158 and laternot affected · rpm
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | thunderbird | before 1:153.5.1esr-1~deb12u1 | 1:153.5.1esr-1~deb12u1 |
| Debian:13 | thunderbird | before 1:153.5.1esr-1~deb13u1 | 1:153.5.1esr-1~deb13u1 |
| Debian:14 | thunderbird | before 1:153.5.0esr-1 | 1:153.5.0esr-1 |
Same product
mozilla: all recordsOther highest-scoring records for the same primary product.
- CVE-2019-11705A flaw in Thunderbird's implementation of iCal causes a stack buffer overflow in icalrecur_add_bydayrules when processing certain email mess42Plan
- CVE-2019-11704A flaw in Thunderbird's implementation of iCal causes a heap buffer overflow in icalmemory_strdup_and_dequote when processing certain email 42Plan
- CVE-2019-11703A flaw in Thunderbird's implementation of iCal causes a heap buffer overflow in parser_get_next_char when processing certain email messages,42Plan
Published before and after this one in the same product
- ← EarlierCVE-2026-103500Sep 30, 2026 · Heap buffer overflow opening large email24Monitor
- ← EarlierCVE-2026-110247Oct 13, 2026 · Integer overflow in libmime buffer growth could lead to heap corruption33Monitor
- Later →CVE-2026-113866Oct 20, 2026 · Account password sent unencrypted during Exchange account setup23Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:thunderbird | 1:153.5.0esr-1 · Debian:14 | Package registry (OSV) |
| debian:thunderbird | 1:153.5.1esr-1~deb12u1 · Debian:12 | Package registry (OSV) |
| debian:thunderbird | 1:153.5.1esr-1~deb13u1 · Debian:13 | Package 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.
- Published
- Fix recorded+8 d
- TodayOct 30, 2026+17 d
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 researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-57962104 days apartDenial-of-service via malicious LDAP address-book server21Monitor
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).
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- No account or password is required.
- A user must open a link or visit a page.
- 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
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-400 · Uncontrolled Resource ConsumptionCVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
nvd-secondary
Root cause
Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.
The bug in code
The whole CWE-400 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
function expand(node) {
return node.children.map(expand);
}Fixed
const MAX_DEPTH = 32;
function expand(node, depth = 0) {
if (depth > MAX_DEPTH) throw new Error("too deep");
return node.children.map((c) => expand(c, depth + 1));
}Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Change log
- Fix✗ → ✓
- CVSS— → 8.6
- Severity— → high
- SSVC exploitation— → none
- Exploit maturity— → none
For records you follow, these changes also arrive as notifications. →
References
Show all references (2 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.